Man—Machine
Julien Offray de La Mettrie

Copyright © Jonathan Bennett 2017. All rights reserved[Brackets] enclose editorial explanations. Small ·dots· enclose material that has been added, but can be read as
though it were part of the original text. Occasional •bullets, and also indenting of passages that are not quotations,

are meant as aids to grasping the structure of a sentence or a thought. Every four-point ellipsis . . . . indicates theomission of a brief passage that seems to present more difficulty than it is worth. Longer omissions are reported
between brackets in normal-sized type.—The most recent translation and edition of this work, by Ann Thomson(Cambridge UP 1996), gives much historical and bibliographical material that is needed for a serious scholarly
study of the work. It also includes translations of other works by La Mettrie that have never before been translated
into English. The original title is L’Homme Machine, an odd bit of French—two nouns side by side—which has tobe translated into odd English. The usual choice has been Man a machine. Ann Thomson’s edition uses Machine
Man, which emits an unwanted whiff of Hollywood. (It was chosen not by her but by the editor of her series.)—The
division into sections is added in this version; it is meant only as a rough guide to the places where new topics
are started on.
First launched: December 2009

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Contents
A start on thinking about materialism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Divine revelation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Some empirical facts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Food . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
Other influences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6Physical constitution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
The ability to learn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Imagination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Humanity’s assets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Attention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Man and the other animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Innocent criminals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
The law of nature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
The existence of God . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
The law of nature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Self-moving body parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
The ‘springs’ of the human machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
More about the organisation of the human body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Feeling and thought . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Solving two ‘riddles’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
From sperm to man . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Reconciling ourselves to our ignorance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
The moral advantages of La Mettrie’s view of man . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

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Divine revelation

For a wise man, it is not enough to •study nature and thetruth; he must be willing to •proclaim it for the benefit of the
few who are willing and able to think. As for the rest—thewilling slaves of prejudice—they can’t reach the truth any
more than frogs can fly.

The wisest have said that the soul can be known only by thelight of faith; but as rational beings they claimed the rightto examine what the Bible meant by the word ‘spirit’, which
it uses when speaking of the human soul. And if in theirresearch they disagree with the theologians on this point,
are the theologians any more in agreement with each otheron everything else?
Here, in a few words, is the result of all their reflections.
(1) If there is a God, he is the creator of nature as muchas of revelation; he gave us the one to explain the other, andreason to reconcile them.
(2) To distrust what we can learn by studying living
bodies is to see •nature and •revelation as hostile opposites,
and consequently to come out with an absurdity—that God
contradicts himself in his different works, and deceives us.
(3) If there is a revelation, it can’t contradict nature. It’s
only through nature that we can discover what the Gospel’s
words mean: experience is the only guide to that. Previous
commentators have only confused the truth. We’ll see an
example of that ·when we look into the work of· the author of
the Spectacle of Nature, ·Abbé Pluche·, who writes this about
Locke:‘It is surprising that a man who debases our soul tothe point of thinking it to be made of clay ventures
to set up reason as the judge and supreme arbiterof the mysteries of faith. What an astonishing ideaof Christianity we would have if we tried to follow
reason!’These reflections, as well as throwing no light on anything to
do with faith, are frivolous objections to the method of those
who think they can interpret the holy books—so frivolousthat I am almost ashamed of spending time refuting them.

A start on thinking about materialism
Philosophers’ theories regarding the human soul? Basicallythere are just two of them: the first and older of the two is•materialism; the second is •spiritualism. [As you will see, thishas nothing to do with the ‘spiritualism’ that traffics in communication
with the dead etc.]

The metaphysicians who implied that matter might wellhave the power to think didn’t disgrace themselves asthinkers. Why not? Because they had the advantage (for inthis case it is one) of expressing themselves badly. To ask
whether unaided matter can •think is like asking whether·unaided· matter can indicate the time. It’s clear alreadythat we aren’t going to hit the rock on which Locke had thebad luck to come to grief ·in his speculations about whether
there could be thinking matter·.
The Leibnizians with their ‘monads’ have constructed
an unintelligible hypothesis. Rather than materialising thesoul ·like the philosophers I have just mentioned·, theyspiritualised matter. How can we define a being ·like theso-called ‘monad’· whose nature is absolutely unknown tous?
Descartes and all the Cartesians—among whom Malebranche’s followers have long been included—went wrong
in the same way, ·namely by dogmatising about somethingof which they knew nothing·. They admitted two distinct
substances in man, as if they had seen and counted them!
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What makes reason excellent is not its being immaterial(what a grand meaningless word that is!), but its force, its
scope, or its acuteness. Contrast these two:
•A soul of clay which tackles countless ideas that are
hard to grasp, and sees at a glance, so to speak, how
they are related to one another and what they imply;•A silly, stupid soul made of the most precious elements.
It is obvious which of these would be the better soul to have!
Blushing at the miserable nature of our origins, as ·theancient Roman naturalist· Pliny did—that’s not behaving
like a philosopher. What seems to be base is here the mostprecious thing, on which nature seems to have expended
the most art and effort. [’. . . is here the most precious thing’—what

can imagine hearing an Aristotelian saying ‘We mustn’t
believe Toricelli’s experiment, because if we did accept it,
abandoning nature’s abhorrence of a vacuum, what a strange
philosophy we would have! [Toricelli did some experiments with a
set-up that is now recognised to be a barometer.]

I have shown how flawed Pluche’s reasoning is1 in order(1) to show that if there is a revelation, it isn’t adequately
established just by the Church’s authority without being
examined by reason, as all those who fear reason claimthat it is; and (2) to shield from attack the method of those
who would like to follow the path that I am clearing forthem, interpreting supernatural things—which, taken on
their own, are incomprehensible—by the lights that each ofus has received from nature, ·i .e. interpreting them by thelights of experience and reason·.

does La Mettrie mean by ‘here’? Perhaps ‘here on this planet’, perhaps

But even if man had come from alower-seeming source ·than mere clay·, he would still be themost perfect of all beings; and if his soul •is pure, noble andsublime, whatever it •is made of, it is a splendid soul that
entitles its owner to respect.
There is a touch of fanaticism about Pluche’s system, buteven on its own terms his second mode of reasoning seems to
me to be flawed: if our idea of faith is contrary to the clearest
principles and the most unquestionable truths, we should
conclude that this idea is false and that we don’t yet know
the meaning of the Scriptures. We owe this to the honour ofrevelation and its author.
Here are two options. Choose one:•Everything—both nature itself and revelation—isillusion.
•Faith can be justified by unaided experience.
Could anything be more ridiculous than our author? I‘here in the case of man’.]1

In this territory, then, experience and observation should
be our only guides. There are countless ·relevant· empirical
data in the records of physicians who were philosophers [here= ‘philosophers or scientists’], not in ·those of· philosophers who
were not physicians. Physicians have explored and thrown
light on the labyrinth of man; they alone have revealed thesprings hidden under coverings that hide so many marvels
from our sight. [The word translated by ‘spring’ in this work is ressort,which refers only to the insides of wind-up machines, and has nothing
to do with natural sources of water.] They alone, calmly surveying
our soul, have many times caught it unawares—in its misery,
without despising it, and in its grandeur, without admiring
it. I repeat: these are the only scientists who have theright to speak on this subject. What could anyone else,
especially the theologians, tell us? Isn’t it ridiculous to hearthem shamelessly holding forth on a subject they are in
no position to understand? It’s not just that (·negatively·)

His mistake is obviously that he assumes the truth of his conclusion as one of his premises.

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they don’t understand it; they have (·positively·) been turned
away from understanding it by obscure studies that have ledthem into countless prejudices—in short, fanaticism—which
increases still further their ignorance of the mechanism of
our bodies.
But although we have chosen the best guides, we’ll stillfind many thorns and obstacles in our path.
Man is a machine—such a complex machine that it’s
initially impossible to get a clear idea of it or (therefore) todefine it. That is why all the research that the greatest
philosophers have conducted a priori—trying to use thewings of the mind, so to speak—have led nowhere. Our only
way to discover the true nature of man is a posteriori, ·i.e.
on the basis of empirical evidence·, trying isolate the soul,as it were disentangling it from the body’s organs. ·When
I speak of what we can ‘discover’·, I don’t mean •discoverwith certainty but merely •reach the highest possible level ofprobability.

all their works? So let us get started, looking not at what
has been thought but at what we should think if we want an
untroubled life.
To each different balance of •bodily fluids or ‘humours’
there corresponds a different mind, character and habits.
Even Galen knew this truth, which Descartes pushed to thepoint of saying that medicine, unaided, could change minds
and habits by changing the body. It is true that each man isdifferent from each other man because of differences in their‘humours’—melancholy, bile, phlegm, blood, etc.; differencesin what kinds they have, how much of each, and how they
are combined.
When someone is ill, ·all sorts of things may happen to·his soul:•his soul drops out of sight, giving no sign that it exists;•his soul is so agitated by the violence of the illness
that it appears to be doubled;•recovery from the illness cures imbecility: in thecourse of convalescence an idiot becomes a cleverman;•the illness makes a really fine mind stupid, so that
he doesn’t even know who he is—farewell all thatsplendid knowledge acquired at such cost and withsuch effort!
. . . .Take the case of a soldier who doesn’t realize that his arm
has been amputated. His illusion—his type of delirium—iscaused by his memory of earlier sensations and of the placein his body that his soul related them to. If we speak to himof the missing part, that will start him off: he’ll remember
it and feel all its movements; and that will create a peculiar
indescribable sort of unpleasure in his imagination. [In theSome empirical facts
Let us, then, ·forget about wings, and use our feet. Let us·
take up the staff of experience and turn our backs on the sadstory of all the futile opinions of philosophers. To be blindand to believe one doesn’t need this staff—that is the heightof blindness! A modern author [in fact, La Mettrie himself] wasright to say that the refusal to appeal to secondary causes
as well as primary ones is sheer vanity! [God or an action ofGod’s may be the •primary cause of that tree’s falling down; if he causes
this by causing a wind that blows down the tree, then that wind is the•secondary cause of the tree’s falling.] We can, we should, admire
all those geniuses—the Descarteses, the Malebranches, theLeibnizes, the Wolffs, etc.—in their utterly useless labours;
but tell me: What did we get from their deep meditations andlast line of the above indented passage, ‘a really fine mind’ translates leplus beau Génie—really meaning ‘the finest genius’? No. Early modern
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and in that weaker sense it will be translated in this version by ‘’intellect’The soul and the body fall asleep together. As the
blood’s movement is calmed, a sweet feeling of peace spreads
through the whole machine. The soul feels itself gentlyor ‘fine intellect’ or the like. When he applies it to ‘the Descarteses’ etc. apage back, La Mettrie surely means it in the strong sense, but ironically.][This paragraph refers to three ancient Romans who faced death byexecution with notable courage and calmness.] Here’s a man who•becoming heavy along with the eyelids,•relaxing along with the brain’s fibres, and thus gradu-cries like a baby at the approach of death, and there’s one
who jokes about it. What would have changed the bravery ofCanus Julius, Seneca or Petronius into shivering cowardice?
An obstruction in the pancreas or the liver, or a blockagein the portal vein. Why? Because ·when either of those
happens· the imagination is blocked along with the organs,and that’s what gives rise to all the varieties of hysteria andhypochondria.
There are people who think •they have been changed
into werewolves, cocks or vampires, or •that they are being
sucked by the dead: what could I say about them that hasn’t
been said already? There are people who think that somepart of them is made of glass and who have to be advised tosleep on straw (‘so that you won’t break’!), so that the straw
can be set alight, causing them to be afraid of being burnt,
which causes the supposedly glass limb to return to being
a usable affair of flesh and bone. (This fear has sometimes
cured paralysis.) But why would I spend time on them? I
ought to skim through facts that everyone knows.
I shan’t spend more time, either, on details of the effects
of sleep. Look at that exhausted soldier! He is snoring in his
trench to the sound of a hundred cannons! His soul hears
nothing, his sleep is complete unconsciousness. A bomb isgoing to crush him and he may feel the blow less than hewould an insect under his foot.
Whereas over there there’s a man who can’t sleep becauseof his jealousy, hatred, greed or ambition. The quietest place,the most soothing cool drinks are all useless for those who
haven’t freed their souls from the torment of the passions.

ally•becoming paralysed, as it were, along with all the

body’s muscles.
The muscles can’t support the weight of the head, while thesoul can’t support the burden of thought. When it is asleep,
the soul is as if it didn’t exist.
If the blood flows too fast, the soul can’t sleep; if the soulis too agitated, the blood cannot calm down—you can hear it
rushing through the veins. These are reciprocal ·event-pairs,
one with the causation running from body to soul, the otherrunning the other way; and yet they are both· causes of
insomnia. A single scare in a dream makes the heart beat
twice as hard, and deprives us of . . . .the sweetness of sleep,
just as would a sharp pain or a full bladder. Finally, as sleep
comes from the mere closing down of the soul’s functions,little sleeps of the soul—day-dreams—. . . .occur even when
one is awake (or, strictly, half-awake). This shows that thesoul doesn’t always wait for the body in order to go to sleep,
for if it isn’t completely asleep ·in a day-dream· it is awfully
close! That can be seen in the fact that the soul can’t pickout a single object that it has paid any attention to; ·that is·,can’t pick it out from the great mass of confused ideas thatare like clouds filling the atmosphere of our brains.
Opium is so closely related to the sleep it brings that it
earns a place in this discussion. This remedy inebriates, as
do wine, coffee, etc., each in its own way, and according to
the dose. The state it puts a man into is the •image of death,and would seem to be the •tomb of feeling, yet it makes the4Man—Machine

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man happy. What sweet lethargy! The soul would like to stay
in it for ever. Having been vulnerable to the greatest miseries,
the soul now feels only the pleasure of •suffering no more
and of •enjoying the most charming tranquillity. Opium evenaffects the will: the soul wants to stay awake and enjoy itself,
but the soul forces it, against its will, to go to bed. I shan’ttalk about the history of poisons.
Coffee is the antidote to wine: by lashing the imagination
it dissipates our headaches and our sorrows without saving
them up for the next morning, as wine does.
Let us think about the soul in its other needs.

Raw meat makes animals ferocious; men would be too,
if that was all they ate. This ferocity gives rise in the soul
to pride, hatred, contempt for other nations, stubbornness,and other feelings that which degrade the character, just ascoarse food makes for a heavy, thick mind that best likes
laziness and inactivity.
[La Mettrie next quotes the English poet Alexander Pope, in Frenchprose. This version will give the original.]

Pope well knew the power of greed, when he said:
Catius is ever moral, ever grave,
Thinks who endures a knave, is next a knave,
Save just at dinner—then prefers, no doubt,
A rogue with ven’son to a saint without.

Food
The human body is a machine that winds itself up, a living
likeness of perpetual motion. The states that fevers •work
up are •kept in a steady state by food. Without food, the soulloses strength, becomes frenzied, and dies worn out—like acandle whose light flares up just as it is going out. But if
you feed the body, pouring into its pipes •vigorous sugars
and strong liquors, then the soul—as full of energy as •they
are—arms itself with proud courage, and the soldier who
would have run away if given water becomes fierce andcheerfully runs towards death to the sound of drums. In
the same way hot water stirs up the blood while cold water
calms it.
How powerful a meal is! Joy revives in a sad heart; itenters the souls of the diners who express it in the charming
songs that the French are so good at. [In an obscure further
sentence, La Mettrie seems to be saying •that good food will
have a bad rather than a good effect on a Mélancolique, thispresumably being someone who is clinically depressed rather
than merely having ‘a sad heart’; and •that a studious person
will have lost the ability to be cheered up by food.](Alexander Pope, Moral Essays)

In Switzerland a certain bailiff. . . .was the most upright andeven indulgent of judges when he was fasting, but heaven
help any poor wretch in the dock when the bailiff had had
a good dinner! He was as apt to hang the innocent as theguilty.
It’s the way our machine is provisioned that makes us
lively or brave, and in the same way it makes us think, andmakes us honest. Sometimes one would say that the soul
lives in our stomach. . . .
What excesses we are led to by cruel hunger! The person
who is starving loses his respect for the bodies that gave him
life and for the ones to whom he gave life [that is, a starving
man will eat his children, or his parents, if there is nothing else to eat];he tears them apart voraciously, making a horrible feast ofthem; and in this frenzy the weakest always fall prey to thestrongest.
5

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Other influences

still further by (2) education, which women don’t get. With
such help from nature and art, how could men not be
more grateful, generous, constant in friendship, firm inadversity etc. ·than women are·? But anyone who combines
grace of mind and body with nearly all the tenderest andmost delicate feelings of the heart shouldn’t envy us thetwofold strength that men seem to have been given only so
as to improve their performance in (1) being drawn by theattractions of beauty and (2) providing pleasures for women.
In saying this I am pretty much following the thought of·Pernetti·, the author of Letters on Physiognomy.

Pregnancy. . . .usually brings depraved tastes in its wake;
but it goes further than that, and sometimes makes the soulcarry out the most atrocious plots, the effects of a sudden
mania that smothers even the law of nature. Thus thebrain—that womb of the mind—undergoes its own kind of
perversion along with the changes in the womb of the body.
[La Mettrie opens this paragraph with an obscure comparison between•pregnancy and pâles couleurs, a plural name for a single infirmity, a•kind of anemia in young women. He associates ‘depraved tastes’ with‘both •these states’.]You don’t have to be as great a physiognomist as Pernetti
to guess the quality of someone’s mind from his face orstrongly marked features, any more than you have to be agreat physician to recognise an illness that is accompanied
by its obvious symptoms. Examine the portraits of Locke,
Steele, Boerhaave, Maupertuis and others: you won’t be
surprised to see that they have strong features and eagle
eyes. Go through countless others, and you’ll always be able
to tell the merely handsome from the intellectually brilliant,and often you’ll be able to tell the honest man from the rogue.

What other kind of frenzy—male or female—occurs inthose who are hunted by continence and good health! Thisshy, modest girl has lost all shame and modesty; worse,
she now considers incest merely as a promiscuous woman
considers adultery. If her needs aren’t promptly met, hertroubles won’t be confined to mere episodes of womb trouble,
mania, and so on; this poor woman will die of an affliction forwhich there are many doctors. [He means, evidently, that she will
die of continence = virginity; it’s obvious why there are ‘many doctors’ forthat ‘affliction’.]

The air ·that we feel and breathe· has great power. . . .
It can happen that a whole people’s minds are heavy andstupid, while the minds of another people are lively, lightand penetrating; and this has to be caused in part by thefood they eat, their fathers’ seed2 and the chaos of different
elements floating around in the immensity of the air. The
mind, like the body, has its epidemics and its scurvy.

If you can see at all, you can see the necessary influenceof age on reason. The soul tracks along with the stages
in the body’s progress as it does also with the stages of
education. In the fair sex, the soul also tracks sensitivityof temperament, which explains the tenderness, affection
and strong feelings ·that women have·, based on passion
rather than on reason; and it also explains such things as·women’s· prejudices and superstitions whose deep imprint
can scarcely be erased. In men, on the other hand, (1) whose
brains and nerves have the firmness of all solids, the mind ismore muscular, as is the face. And their soul is strengthened
2

The climate is so dominant that someone who changes
climates is affected by that change, whether or not he wants
to be. He’s a wandering plant that has transplanted itself; if
the climate changes then the plant declines or improves.

The history of animals and men proves the influence of the father’s seed on the minds and bodies of their children.

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We copy everything from those we live with—gestures,
accents, and so on—doing this as involuntarily as the eyelid
blinks when it sees a blow coming, or as a spectator’s
body imitates mechanically, and despite himself, all the
movements of a good mime.
Those remarks show that a thinking man who can’t findanyone else like himself will be his own best company. If hekeeps company with people who don’t think, his mind will
get rusty; in tennis, we return the ball badly when it is badly
served. Rather than being with an intelligent man who has
had a bad education, I would prefer one who has had no
education, provided he is still young enough. A badly trained
mind is ·like· an actor who has been spoilt by provincial
theatres.

After all the quadrupeds, it’s the birds that have the mostbrain. Fish have big heads, but they are empty of sense, likethose of many men. They have no corpus callosum and very
little brain. Insects have no brain at all.
If you read Willis’s The Brain and The Soul of Brutes, you’ll
see that there’s no end to the •details of nature’s variety or
to the •speculations one might offer about them; so I shan’t
go into •either.
I shall simply draw a conclusion that obviously follows
from these incontrovertible observations: (1) the more ferocious an animal is, the less brain it has; (2) the brain seems
to grow in some way in proportion to ·its owner’s· ability tolearn; (3) here we see that nature always does, and always
will, ensure that what is gained on the side of intelligence islost on the side of instinct. Which is greater, the loss or thegain?
I am not claiming that the volume of an animal’s brain
tells us, unaided, how good the animal is at learning. ·Foran animal to be high on that scale·, the •quality of its brain
must correspond to its •quantity, ·i.e. its size·; there must
be a healthy balance between the solids and the fluids.
A ·congenital· idiot does have a brain (he is often said
not to), but it tends to have a bad consistency—for example,
being too soft. It is the same for lunatics: we can sometimes
examine the defects of their brains. But if the causes of
idiocy, madness, etc. are not easy to see, how can we hope tofind the causes of the difference between one ·sound human·
mind and another?. . . .
In addition to the softness of the brain marrow in children,
puppies and birds, Willis remarks that the corpora striata
are discoloured and hard to see in all these animals, and that
their streaks are as imperfectly formed as in paralytics. He
adds (and he’s right) that man has a very large pons varolii,
and that this part of the brain is steadily smaller as we move

Physical constitution
So the soul’s various states are always correlated with the
body’s. But to make a better job of exhibiting this dependence and its causes, let us bring in comparative anatomy.
Let us get into the entrailles [= ‘innards’] of men and animals.
How are we to know human nature if we aren’t informedby an accurate comparison of the structures of men andanimals?
In general, quadrupeds’ brains are pretty much the samein form and composition as man’s brain. Everywhere—sameshape, same arrangement; with just this essential difference:
relative to body-size, man has the biggest and most convoluted brain of all the animals. Next come the ape, beaver,elephant, dog, fox, cat, etc.; these are the animals that are
most like man, for they can be compared among themselves
on a scale having to do with the corpus callosum, which
Lancisi said was the home of the soul, an opinion that thelate M. de la Peyronie illustrated with a mass of experiments.
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to the ape and then on through the other animals that I
listed; whereas the calf, ox, wolf, sheep, pig, etc.—in which
the pons variolii is very small—have very big nates and testes.

be remedied? In short, would it be absolutely impossible toteach a language to such an animal? I don’t think so.
My best candidate for this would be the great ape [= theOrang-outang], unless we happened to discover some otherspecies that is even more like ours, as we well might in someregion that hasn’t yet been explored. The great ape is solike us that naturalists have called it the ‘wild man’ or the‘man of the woods’. I would select one that •was neither
too young nor too old (most of the ones brought to Europe
are too old), and that had the cleverest physiognomy andconfirmed this promise in a thousand little tests. Finally,
as I am not up to the job of being its tutor, I would send it
to the excellent Amman’s school or to the school of someother equally skilful teacher, if there is one. [J. K. Amman, a[These two words are Latin for ‘buttocks’ and ‘testicles’ respectively; but
for some reason they were adopted in the 17th and 18th centuries toname parts of the brain.]

What are we to make of these and many other observations concerning the—let’s call it—inconstancy of vessels andnerves, etc.? It’s all very well to be cautious and sparing in
drawing conclusions, but there’s one thing we can say about
all this, namely that all this variety can’t merely show natureplaying meaningless games with us. They show at least theneed for a good and rich organisation, because throughout
the animal kingdom the soul becomes firmer along with thebody, and acquires wisdom in proportion as the body gains
strength.

Swiss physician and author of Surdus loquens = ‘The talking deaf man’,developed a system for teaching congenitally deaf people to speak.] My

The ability to learn

criteria for selecting my great ape pupil, incidentally, are theones Amman uses in selecting children for his school.

Think about the differences in animals’ ability to learn.
Sound analogical thinking leads the mind to believe that thecauses I have mentioned are the source of all the differences
between the other animals and ourselves; though we must
admit that our feeble understanding, being restricted to thecrudest observations, can’t see the ties linking the cause
to its effects. The cause-effect tie is a sort of harmony thatphilosophers ·and scientists· won’t ever understand.
•Some animals learn to talk and sing; they remember
tunes and get all the notes as exactly as any musician.
•Others (such as the ape) display more intelligence and yet
can’t manage this. Why is this, if it’s not because of a defectin the speech organs?
But is this defect built into the animal so that it can’t

You know, from Amman’s book and from all those whohave presented his method,3 all the wonderful results he
has achieved with children born deaf, in whose eyes he has
discovered ears (that is how he puts it), and how quickly hehas taught them to hear, speak, read and write. I think thata deaf person’s eyes see better and more alertly than theeyes of someone who isn’t deaf, because the loss of one limb
or one sense can increase the strength or the sharpness ofanother. But the ape sees and hears, it understands what ithears and sees. It grasps so perfectly the signs that are madeto it that I’m sure it would do better than Amman’s pupils at
any game or exercise that didn’t involve language. Why thenshould the education of apes be impossible? Why couldn’t ahard-working ape reproduce for itself the sounds needed for3

The author of The Natural History of the Soul etc. [this author was La Mettrie himself].

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pronunciation, achieving this—as the deaf do—by imitation?
Well, it might be that the ape’s speech organs can neverarticulate anything, whatever we do ·in the way of teaching·;
I don’t venture to pronounce on that question. But I’d besurprised if it were right, given the close analogy between
ape and man, and the fact we have never found any ·other·animal that is so strikingly like man, inside and outside, as
the great ape is. Locke was never suspected of credulity, andhe saw no obstacle to believing Sir William Temple’s accountof a parrot that. . . .had learned, as we do, to conduct a sortof coherent conversation. I know that some have made funof this great metaphysician,4 but if someone had announced
to the world that ·some· animals can reproduce without eggs
and without females, would he have found many supporters?
Yet Trembley has discovered such animals, which reproduce
by simple division, without mating. [These were polyps, of which
we shall hear more in item 10 on page 23.] And wouldn’t Amman
have been regarded as mad if he had boasted, in advance of
having any results, that he could teach pupils like his, and insuch a short time? Yet his success has astonished everyone,and like Trembley he has shot up into immortality. I rank
someone who owes the miracles he performs to his own
intellect above one who owes his miracles to chance. Anyone
who discovers how to make things even better in the finestof kingdoms, providing perfections it didn’t have, should bevalued more than an •unemployed maker of futile systems
or a •hard-working author of sterile discoveries! Amman’s
discoveries have a different order of value; he has saved men
from the mere instinct to which they seemed condemned;
he has given them ideas, a mind—a soul—that they would·otherwise· never have had. How much greater this power
is!. . . .
4The mechanism that opens the Eustachian tube in thedeaf—couldn’t it also unblock it in apes? An amiable wish
to imitate the master’s pronunciation—couldn’t that free theorgans of speech in animals that can imitate so many othersigns with such skill and intelligence? I defy anyone to point
to a single truly conclusive experiment showing that my planis impossible and absurd; and I go further—I am virtuallycertain, given the ape’s similarity to us in structure andoperations, that if we went about it in the right way we could
teach this animal to utter sounds and consequently to learn
a language. Then it would no longer be a ‘wild man’ or animperfect man, but a perfect man, a small ‘man of the town’·as against ‘man of the woods’·, with as much material—asmuch muscle—for thinking and profiting from its education
as we have.

There’s no sharp line between animals and man; true
philosophers would agree about that. What was man before
he invented words and learned languages? ·Back then·a member of the human species, with much less natural
instinct than members of other species (he didn’t yet think
he was their king!), was distinguishable from apes and otheranimals only by having a facial structure that indicatedgreater discernment (which is what now marks off apes
from other animals). Reduced to raw sensory knowledge. . . .,he saw only shapes and colours, without being able todistinguish any of them. A perpetual child (whatever hisage), he stuttered out his sensations and his needs, like ahungry dog wanting to eat or a restless one wanting to betaken for a walk.

For example, the author of The Natural History of the Soul.

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Languagecame from the playwright and man of ideas Bernard le Bovier Fontenelle,
who reported that the deaf man began to speak only a few weeks after

Words, languages, laws, science and arts came, and throughthem the rough diamond of our minds was at last polished.
Man was drilled like an animal; he was trained into being an
author in the same way as ·a dog, for instance is· trained tocarry a pack. A mathematician learned how to conduct themost difficult proofs and calculations, as a monkey learns to
don and doff his little hat or ride his trained dog. Everything
was done by signs; each species understood what it could
understand; and that is how man acquired what our German
philosophers call symbolic knowledge.
You see, nothing is simpler than the mechanism of oureducation! It all comes down to sounds, to words, which gofrom x’s mouth through y’s ears to y’s brain, which receivesat the same time through y’s eyes the shape of the bodies
that x’s words are the arbitrary signs of.
But who spoke first? Who was the first tutor of the humanrace? Who devised the means to make the best use of ourconstitutional capacity for learning? I don’t know; the namesof those first geniuses—bless them!—are lost in the mistsof time. But art is the child of nature, and nature musthave long preceded it. [In this context, ‘art’ refers to anything thatsuddenly becoming able to hear.]

It isn’t absurd to believe that those first ·intellectuallywell-equipped· mortals tried—like that deaf man or like animals and dumb people (who are another sort of animals)—toexpress their new feelings and experiences by •movements
provided by their imagination, leading in due course to spontaneous •sounds—different sounds for each animal—thisbeing a natural expression of their surprise, joy, emotions orneeds. For doubtless those whom nature endowed with morerefined feelings were also given greater facility to express
them.
That is how I see men as having used their feelings ortheir instinct to acquire intelligence [esprit, often merely meaning‘mind’], and used their intelligence to acquire knowledge.
Those are the means, as far as I can grasp them, by which
they filled their brain with the ideas that nature had built
them to receive. They helped one another ·in this task·;
and from small beginnings their abilities gradually increased
until they could pick out any object in the world as easily as
they could a circle.
Just as a violin string. . . .vibrates and makes a sound, so
also the strings of the brain, struck by sound-waves, were
stimulated to give out or repeat the words that reached them.

involves inventiveness, techniques, rules, skill; so linguistic competence
is an ‘art’.]We must suppose that the men who were best constituted,
those on whom nature has lavished its benefits, will havetaught the others. They couldn’t have heard a new sound, experienced new feelings, or been struck by all the enchanting
beauties of nature, without finding themselves in the same
position as the famous deaf man from Chartres. . . .who at
the age of 40 heard for the first time the astonishing sound ofbells. [What ‘same position’? Presumably: having something amazing
to report, and no means to report it.

[In that first clause, La Mettrie probably set out to say: ‘Just as a violin
string, when a certain sound reaches it, vibrates and makes that same

But the brain is constructed insuch a way that as soon as the optically competent eyes
have received pictures of certain objects, the brain can’t
help seeing what they are like and how they differ from one
another. ·Now, carrying this general account of the brain
back into the very early days of language and knowledge·,when the signs for these differences were marked or engraved
sound on its own accord. . . ’.]

The account of the deaf man

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on the brain, the soul had to examine the relationships
between them; and this examination wouldn’t have beenpossible without the discovery of signs or the invention of
languages. [The next clause speaks of a time when the world was

and less perceptible are harder to learn than other truths,
because it takes a higher level of intellect to grasp andcombine the vast quantity of words that the sciences inquestion use to express their truths; whereas sciences that
present themselves through figures or other small signs
are easy to learn; and no doubt it’s this ease that led tothe success of algebraic calculations, more even than theirevidentness.
So all the windy learning that inflates the brain-balloonsof our haughty pedants is merely an enormous mass ofwords and figures, which create in the head all the tracesby means of which we recall objects and distinguish themfrom one another. . . . These words are so closely linked in
the brain to the figures they represent that we very seldom
imagine an object without ·imagining·the name or sign thatis attached to it.

‘silent’ = it didn’t ‘speak to’ human beings = they didn’t know what to

At the time when the world was almost silent,
the soul confronted all those objects in the manner of aman who has no idea of proportions looking at a picture
or a sculpture, with no ability to pick out parts of it ·andsee their significance within the whole·. Or in the mannerof a little child (back then the soul was in its childhood)holding in its hand some bits of straw or wood, having avague and superficial intake of them as a bunch but not
being able to count or differentiate them. But if we taketwo indistinguishable pieces of wood and attach to one a
tag bearing the numeral ‘1’ and to the other a tag with
the numeral ‘2’, then the child will be able to count them,and this will set him on the way to learning the whole ofarithmetic. As soon as one external spatial item seems to
him to be equal to another by its numerical sign—·i.e. equalin the sense that each of them is one item·—he’ll easily
conclude these are two different bodies, and that 1 and 1
make 2, that 2 and 2 make 4, and so on.5
make of it.]

Imagination
I keep using the word ‘imagine’ because I believe •that
everything is imagined and •that all the parts of the soulultimately come down to imagination, which creates themall, and thus •that judgment, reason and memory are partsof the soul that are in no way absolute but. . . [The next partof this sentence is so condensed that it is hard to translate
in a way that makes its point clear. It says that these ‘parts’of the soul are in no way marked off as absolutely distinct
from the rest. They are merely regions of the soul thatare differentiated from •their surroundings only by being
qualitatively different from •them. The region that contains
them all, our author continues,] is that sort of medullary
screen on which the objects depicted in the eye are projected
as in a magic lantern. But if that is the wonderful andThis real or apparent similarity of external spatial items
is the ultimate basis for all truths and all our knowledge.
(I say ‘. . . or apparent’ not because •I think that our senses
always deceive us, as Malebranche said they do, or because•I think that our eyes, naturally slightly inebriated, don’t
see objects as they really are (though microscopes daily
prove that they don’t), but because •I don’t want to get
into any argument with the Pyrrhonians [= ‘extreme sceptics’],
most notably Bayle.) The truths whose signs are less simple
5

There are still people today whose stock of signs isn’t big enough to let them count higher than 20.

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incomprehensible result of how the brain is organised, if
everything is conceived by the imagination, if everything is
explained by it, then why divide up

roles.
It is through imagination—through its flattering •brush—that
the cold skeleton of reason is covered in living rosy flesh.
It’s through imagination that the sciences flourish, thearts create beauty, forests speak, echoes sigh, rocks weep,
marble breathes and all inanimate objects come to life. It
is imagination that adds to the tenderness of a loving heart
the stimulating attraction of sexual pleasure. Imagination
makes pleasure take root in the study of the philosopher orthe dusty pedant, and it makes scientists as well as oratorsand poets. Some people stupidly criticise it, while others
emptily treat it as special; neither knows much about it.
Imagination doesn’t only follow in the train of the Graces andthe fine arts; as well as •painting nature it also measures
it. [Or ‘. . . measures her’. French doesn’t distinguish these; but thishow La Mettrie finished this sentence: le principe sensitif quipense dans l’homme?
routinely translated: the sensitive principle that thinks inman?
actually meaning: the ·whatever-it-is that is· the source offeeling and thought in man?
[The French principe, like the English ‘principle’ at that time, had two
meanings: (i) as standing for a kind of proposition, (ii) as meaning
something like ‘source’ or ‘cause’ . The remaining seven occurrencesof principe with this meaning—all of them on pages 22–28—will be translated here by ‘principlec ’, with the subscript suggesting ‘cause’.]

Isn’t this a plain contradiction by the supporters of themind’s simple nature? When we divide something we can’t
regard it as indivisible! See where we’re led by the misuse oflanguage and the haphazard use of grand words like ‘spirituality’ and ‘immateriality’ etc. which no-one understands.
Nothing is simpler than to prove a system that is founded,
like this one ·of mine·, on each individual’s private feelingsand experience. If the imagination—a. . . .part of the brain
about whose nature we know as little as we do about its
workings—is naturally small or weak, then it will scarcely
have the strength to note similarities amongst its ideas; itwill be able to see only what is in front of it or what affects
it most vividly, and it won’t make a good job of seeing even
that! But it’s true all the same that• only the imagination perceives; that• it makes representations of all objects, along with thewords and figures that characterise them; and thusthat thus—I’ll say it again—• the imagination is the soul, because it plays all its

version will treat nature as feminine only in places where La Mettrie
seems to be thinking of it in personal terms.] It reasons, judges,
compares and deepens. ·And there are close connections
between imagination’s two sides.· Could it have such agood sense of the beauty of the pictures that are drawn
for it without understanding their relationships? [He means:‘. . . without understanding the relationships amongst their parts’.] No.

The rest of this paragraph: Comme elle ne peut se replier surles plaisirs des sens sans en goûter toute la perfection ou lavolupté, elle ne peut réfléchir sur ce qu’elle a mécaniquement
conçu, sans être alors le jugement même.
Literal translation of that: Just as it can’t fall back on
the pleasures of the senses without appreciating all theirperfection, all their sensuality, so also it can’t reflect on what
it has conceived mechanically without then becoming ·thefaculty of· judgment itself.
Meaning: ?

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The more the imagination or the feeblest intellect is
exercised, the more well-padded (so to speak) it becomes, themore it grows, becomes vigorous, robust, wide-ranging, andable to think. Even the best constitution needs exercise.

what he is getting at: . . . doing this in the spirit of some-

one who is interested in how nature’s advantages are
distributed—perhaps an expert on this topic—not favouring some distributions over others. (Compare: •an expert
wine-critic versus •a spokesman for one particular vineyard.)
A beautiful woman who thinks she is ugly would be as
ridiculous as a clever man who thinks he is stupid. Exaggerated modesty (a rare defect indeed!) is a sort of ingratitude
towards nature. Honest pride on the other hand is the markof a fine, great soul, indicated by manly traits moulded byfeeling.
If organisation is the first asset, and the source of all theothers, then instruction is the second. Without it, the best
constructed brain would be wasted, just as the most handsome man would be merely a crude peasant if he didn’t know
how to behave in society. But ·also, conversely, education isuseless if spent on someone who is constitutionally incapableof profiting from it·. . . . [La Mettrie’s two-sentence expansion of

Humanity’s assets[In this context, the verb estimer will be translated as ‘(give moral) respect(to)’ or ‘admire’. In each case the choice is stylistic, not theoretical.]Man’s first asset is his physical constitution. All moral
theorists refuse to give moral respect to •qualities that are
given by nature; they give it only to •talents acquired byreflection and hard work. This is just wrong. Where docleverness, knowledge, and virtue come from, if not from adisposition—·a physical constitution·—that makes us apt tobecome clever, learned and virtuous? And where does that
disposition come from if not from nature? All our admirable
qualities come from nature; to her we owe all that we are. So
why wouldn’t I admire •people who have ·excellent· naturalqualities as much as •those who shine because of theiracquired (as it were borrowed) virtues? All merit deserves
respect, wherever it comes from; we only need to know how
to measure it. There is value inwit, beauty, wealth, and nobility,
although they are children of chance, just as there is in
dexterity, knowledge, virtue, etc.,·which are not products of chance, i.e. are not directly given
by nature·. Those who have been showered with nature’s
most precious gifts should feel sorry for those who haven’t;
but they can be aware of their advantages without being vain
about them,. . .

this point includes an apparently irrelevant mention of ‘the senses’, apun on matrice that can’t be reproduced in English, a gynaecologicalanalogue that doesn’t fit very well, and a gynaecological anecdote that
adds nothing.]

But a brain that is both well organised and well educatedis a fertile and perfectly seeded plot of ground that produces
a hundred times what it has received. (This figurative styleof writing often lets the writer •express better what is felt
and •add grace to truth itself; ·but I now switch to something
more literal·.) When an imagination is raised by art—·i.e.
by human intervention in the form of education·—to thesplendid, rare dignity of being intellectually first-rate, it seizes
exactly all the relations of ideas it has conceived, and easily
takes in an amazing crowd of items so as eventually todeduce from them a long chain of consequences. These
consequences are merely new relationships, born from a

how La Mettrie ends that sentence: . . . en connaisseurs.
meaning: . . . as connoisseurs.

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La Mettriecomparison with the first ones, with which the soul finds
a perfect similarity. In my view, that is how the mind isborn. . . .
I say about truth in general what Fontenelle said aboutsome truths in particular, namely that it must be sacrificed
to social convenience. My mildness of character makes me
avoid all disputes except in cases where a dispute would
make the conversation sharper and livelier. Cartesians would
be wasting their time charging in with their ‘innate ideas’:
I wouldn’t put in a quarter of the effort that Locke did in
refuting such fantasies. What’s the point of writing a big bookestablishing a doctrine—·namely that there are no innate
ideas·—that was set up as an axiom three thousand years
ago?
Following the principles we have presented and think tobe true, the person with the most •imagination should be
regarded as the one with the most •mind [esprit ] or the most•intellect [génie ], for these three expressions are synonymous;and when we utter different words or different sounds withno real idea or distinction attached to them, it is—I’ll say it
again—an embarrassing blunder if we think we are saying
different things .
So the finest, greatest or strongest imagination is themost suitable for both the sciences and the arts. I am notpronouncing on •whether it takes more intelligence to excel
in the art of Aristotle and Descartes and their like thanin that of Euripides and Sophocles and their like; or on•whether nature ‘spent’ more on producing Newton thanon creating Corneille (though I strongly doubt that it did!).
But it is certain that what gave these men their different
triumphs and their immortal glory was their different usesof their imaginations.
When someone is said to have ‘little judgment but muchimagination’, this means that his imagination, left too muchto its own devices and almost constantly engaged in looking
at itself in the mirror of its own sensations, •hasn’t acquireda strong habit of examining closely those sensations themselves, and •is more deeply interested in things’ traces orimages than in the truth of them, what they are ·really· like.

Attention
It is true that the imagination’s springs [see note on page 2] areso lively that it can only glimpse or skim over the surfacesof objects unless it gets help from attention, the key to thesciences—the mother of the sciences!
Look at that bird on the branch—always seeming readyto take flight. The imagination is like that, always swept
along by the swirl of the blood and the spirits: a trace leftby one wave is washed away by the next. The soul chases
after them, often in vain. It can count on missing the ones
that it wasn’t quick enough to seize and pin down. Thus theimagination is constantly destroyed and renewed, just liketime, of which it is an image.
Our ideas come into our minds in a fast-moving jumble,
pushing one another along. If the imagination is to deserve
its fine label ‘·faculty of· judgment’, it has to (so to speak)use some of its muscles to stand upright on the brain’s·tight·ropes, staying for a while above a fleeing object·so as to contemplate it before it disappears·, andpreventing itself from falling ·off the rope· onto anotherobject whose time for contemplation hasn’t yet come.
If it doesn’t do that, it will express vividly what it has felt
vividly; it will make orators, musicians, painters, poets—and not a single philosopher! On the other hand, if fromchildhood the imagination has been accustomed to•disciplining itself,•not being swept along by its own rush,. . . .
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La Mettrie•stopping its ideas and pinning them down, and•looking at them from every angle so as to see all sides

pleasures that await him in the reproduction of his species;
an adolescent already, but he knows little about how toplay the game that nature teaches animals so quickly; hehides, as though it were shameful to feel pleasure and to
be made for pleasure, while animals glory in being Cynicsof them,then the imagination will be poised to judge. Its reasoning
will enable it to take in the greatest range of objects; andits liveliness—which is always so promising in children, andonly needs to be disciplined by study and exercise ·to be ofgreat value to the adult·—will become simply the sharp andinsightful vision without which scientific progress can’t be
made.
These are the simple foundations on which the structureof logic has been built. Nature laid them for all the humanrace, but ·only· some have profited from them, while others
have misused them.

[i.e. followers of the philosopher Diogenes, who claimed to return to his
natural state and to reject social rules and conventions]. Having no

education, they have no prejudices. But, again, look at that
dog and that child who have both lost their master on the
highway: the child is crying and doesn’t know which way toturn, whereas the dog will soon find its master, having been
helped more by its sense of smell than the child was by his
reason.
So nature made us •to be beneath the animals, or atleast •to exhibit vividly the great achievements of education,
which is the only thing that can remove us from that leveland eventually place us above the animals. But shall we
extend that same distinction to•the deaf,•those born blind,•idiots,•lunatics,•wild men, i.e. ones have grown up in the forests withanimals,•those whose imaginations have been wiped out by
hypochondria, or•the brutes in human form who display only the crudest instincts?
No! These men-in-body who are not men-in-mind don’t
deserve to be put in a special class of their own. [ItMan and the other animals
Despite all the ways in which man is superior to the ·other·animals, putting him in the same class as them is doing him
a great honour. The fact is that up to a certain age he ismore of an animal than they are, because he is born withless instinct.
Which animal would die of hunger in the middle of a riverof milk? Man alone!. . . . ·If he is armed only with what heis born with·, he doesn’t know that some food is good for
him, that water can drown him, or that fire can turn him
into ashes. Shine candlelight in a child’s eyes for the firsttime and he will automatically stretch out his fingers to it,as thought wanting to ·hold it in his hand, and· examineit; he’ll pay a price for learning how dangerous it is, but hewon’t need to learn it twice.
Or put him with an animal on the edge of a cliff; only hewill fall. He will drown while the other will swim to safety.
At the age of fourteen or fifteen he hardly glimpses the great

seems, then, that the ‘same distinction’ that is in question here is notthat of being-above-the-other-animals but merely belonging-to-a-singlelegitimate-class.]

I don’t mean to ignore the objections that can be made,15

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against my opinion, in support of a basic distinction between
man and animals. Some say that there’s a law of nature inman, a knowledge of good and evil, that hasn’t been engravedon the hearts of animals.
A philosopher is entitled to reject any opinion that isn’t
based on experience—does this objection (this ·mere· assertion) have any such basis? Have we experienced anything
to convince us that some ray of light has fallen on man
and been denied to all other animals? If not, then we can’tknow empirically what happens inside animals or even what
happens inside ·other· men, any more than we can not feel
what happens inside ourselves. We know that we think andthat we feel remorse, as an inner feeling forces us to admit
only too well; but this feeling of •ours doesn’t enable us tojudge remorse in •others. So our beliefs about remorse inother men have to be based on what they say or on externalsigns, i.e. on their behaving in the way we do when we feelthe pangs of conscience.
How could we know that speechless animals have been
given the natural law? It would have to be on the basis ofthe ‘external signs’ that I have just mentioned, if there areany. The facts seem to show that they do. A dog that bitesits master. . . .seems to repent the very next moment; it looks
sad, upset, not daring to show itself, and admitting its guilt
by its humble cringing. History gives us the famous example
of a lion that wouldn’t savage a man who had been thrown
to it, because it recognised him as his benefactor. If only
men would always show the same gratitude for kindness andthe same respect for humanity! Then we wouldn’t have tofear being met with ingratitude, or to fear these wars thatare the scourge of the human race and the real hangmen of
the law of nature. [A fairly widespread and lengthy war was going on

But a being•to whom nature has given such a precocious, enlightened instinct,•who judges, synthesizes, reasons and deliberates as
far as the sphere of its activity extends and allows,•who recognizes benefits received and who reacts to
ill-treatment by pulling away and trying to find abetter master,•whose structure is like ours,•who acts as we do, and•who feels the same passions, pains and pleasures(more or less vividly, depending on the power of its
imagination and the delicacy of its nerves)—doesn’t such a being show clearly that it has a sense ofwrongdoing both in itself and in us, that it knows the difference between good and evil, and (in short) that it is ·morally·
aware of what it is doing? Its soul displays the same joys, thesame humiliations, the same setbacks as we do—would sucha soul be able to look calmly and comfortably at the sightof a fellow creature being torn to pieces. . . .? The animals
give us obvious signs of repentance and of intelligence, so
why is it absurd to think that beings—machines almost as
well-made as we are—were made like us to think, and tohave a sense of ·the demands of· nature?
You may say: ‘Animals are mostly ferocious beings that
can’t have any sense of the harm they do.’ Well, are all men
better able than the animals to distinguish vice from virtue?
There’s ferocity in our species as in theirs. Barbarous men
who habitually infringe the law of nature are not as upset
by what they have done as are those who break the law ofnature for the first time and who haven’t been hardened
by bad examples. Animals and men are alike in this: they
can be temperamentally more or less ferocious, and they
become even more so when they are in fierce company. But

in Europe while La Mettrie was writing this work—hence his reference to‘these wars’. He was sometimes involved in them as a military doctor.]

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a gentle, peaceful animal living on bland food in the company
of others like it will be opposed to blood and massacres; itwill be ashamed of having spilled blood. There is perhaps thisdifference between them and us: for the animals everythingis sacrificed to needs, pleasures and comfort, which they
enjoy more than we do; and their remorse apparently doesn’t
have to be as strong as ours because our needs are not asstrong as theirs. Habit blunts [émousse] and perhaps evenstifles [étouffe] remorse, as it does pleasure.

always distinguish people who are honest, humane, andvirtuous from ones who are none of those, and that •it iseasy to distinguish vice from virtue by the special kinds ofpleasure and revulsion that are their natural effects, then it
follows that animals—being made from the same materials,
with perhaps only a higher level of fermentation needed tomake them the complete equals of men—must share in all
the privileges of animal nature; and that thus there is nosoul or feeling substance that doesn’t have remorse. These
reflections are strengthened by the following one.

If I am right about this, then almost everyone else in
the world is wrong, and you may think that that isn’t fair!
Well, then, suppose for a moment that I am wrong. (1)Suppose that •even the most excellent animals don’t know
the difference between moral right and wrong; that •they
have no recollection of kindnesses that have been done tothem and no awareness of their own virtues; that •thatfamous lion I mentioned doesn’t remember having refused tokill the man who was inhumanly and brutally thrown to it in
the arena. ·Now set that supposition alongside some plain
facts·. (2) Men from the same country,. . . .from the samefamily even, identify one another as enemies, fight against
one another, chain each other up, or kill each other, andthey have no remorse because a prince is paying for thesemurders. What is the result of putting (2) these facts together
with (1) the supposition that the law of nature was not given
to animals? Man isn’t moulded from a more precious clay;
nature has used only one ·kind of· dough, merely varying
the yeast. So if animals are totally deprived of the innerfeeling I have spoken about (the feeling that could lead totheir repenting their conduct), then man must be in the same
situation—in which case farewell to the law of nature andto all the fine books about it! The whole animal kingdom
would be deprived of it. But we can run the argument theother way: If man can’t avoid admitting that. . . .•he can

Innocent criminals
The law of nature cannot be destroyed; its imprint in all
animals is so strong that I’m quite sure that even the mostsavage and fierce of them have moments of repentance. I
believe that if the wild girl from Châlons in Champagne
really did eat her sister, she will have suffered for her crime.
The same is true I think, of everyone who commits a crime,
even if it was involuntary, i.e. was dictated by the person’s
temperament ·in such a way that he couldn’t help acting as
he did·. For example:•Gaston d’Orléans, who couldn’t help stealing;•a woman who was afflicted by the same vice during
pregnancy and passed it on to her children;•a woman who in her pregnancy ate her husband;•another woman who cut her children’s throats, salted
their bodies and ate a piece every day as a snack;•a daughter of a cannibal highwayman who became
one herself at the age of twelve, although she had lost
both parents at the age of one and had been brought
up by respectable people;
not to mention the many other examples that fill the pages ofreporters on the social scene and that all show that hundreds
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a criminal; I claim only that those in whom ·temporarily·
the will is corrupt and the conscience silenced are punished enough by remorse when they recover their senses.
I would even go this far: nature should have spared those
unlucky creatures—the ones who are driven on by irresistible
necessity—from ·the punishments of· remorse.
The criminal, the wicked, the ungrateful and those whoare impervious to nature—miserable tyrants who don’t deserve to live—may get cruel pleasure from their barbarity,
but it won’t do them much good, because they will havecalm moments of reflection when their avenging consciencespeaks up, testifying against them and condemning them tobe almost incessantly shredded by their own hands. Anyone
who torments men is tormented by himself; and the evils hesuffers will be a gauge of how much evil he has caused.
On the other hand, there is so much pleasure in doing
good, in feeling and appreciating the kindness we receive, somuch satisfaction in practising virtue, in being good-natured,humane, tender, charitable, compassionate and generous(this word alone includes all the virtues), that I hold thatanyone who is unlucky enough not to have been born
virtuous is sufficiently punished ·just by that fact·.

of hereditary vices and virtues are passed on to children fromtheir parents, just as the vices and virtues a wet-nurse arepassed on to the children she suckles. So I concede thatthese unlucky folk mostly don’t realise how bad their crimes
are while they are performing them. For example, bulimia—·so-called· canine hunger—can extinguish all feelings; it’s amadness of the stomach that one is forced to satisfy. But
when those women recover their senses and are sobered up(so to speak), what remorse they feel when they remember
murdering what they held dearest! What punishment for an
involuntary evil that they couldn’t resist and weren’t awareof! But that is apparently not enough for the judges. Of thewomen I have mentioned, two were sentenced to execution
by brutal methods [and he gives details]. I am aware of what
the interests of society require. But I’m sure it would bebetter if all judges were first-rate physicians, because only
physicians could tell the innocent criminal from the guilty
one. How can reason govern a depraved or frenzied sense if
it is that sense’s slave?
But •if crime brings its own more or less cruel punishment, •if the longest habit of barbaric behaviour can’t
completely erase repentance from the most callous of hearts;•if they are torn apart by the mere memory of what they
have done—why terrify weak people’s minds with imagesof hell, demons, and walls of fire that are even less real
than Pascal’s?6 As an honest Pope once asked, why do weneed to resort to fables in order to torment the miserable
beings whom we put to death because we don’t think they
are punished enough by their first torturers, i.e. their own
consciences? I don’t mean that it is never just to punish
6

The law of nature
We weren’t originally made to be learned, and our having
become learned may result from a misuse of our organic
faculties; and we’ll have done this at the expense of the State,
which maintains a crowd of idlers whom vanity has deckedout with the label ‘Philosophers’. •Nature created us all solely

In a group of people or at meals he always needed a rampart of chairs or a person near him on his left to block his sight of the terrifying depths that hewas sometimes afraid of falling into—though he knew this was a delusion. What a terrifying effect of the imagination, or of a pathological circulationin one of the brain’s lobes! A great man on one side, he was half mad on the other. ·In Pascal·, madness and wisdom each had its department, itslobe. . . .

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to be happy—yes, all, from the earthworm to the eagle up in
the clouds. That’s why •she gave all animals a portion of thelaw of nature; how refined a portion any given animal gets
depends on what its organs, in their healthy state, can copewith.
How, these days, are we to define the law of nature?
It is a sentiment [a French word that can mean ‘feeling’ or ‘belief or
opinion’] that teaches us what we ought not to do, steering by
what we wouldn’t like to have done to us. Dare I add to thisgenerally accepted idea that in my opinion this sentiment[now he comes out with it: feeling] is only a kind of fear, a scare,that is as good for the species as it is for the individual? For
perhaps we respect the purses and lives of others only so as
to protect our own goods, our honour and ourselves, like theChristians. . . .who love God and embrace so many illusory
virtues only because they are afraid of Hell.
You can see that the law of nature is only an innerfeeling that belongs to the imagination, along with all theother ·things I have assigned to the imagination·, including
thought. So, obviously, it doesn’t presuppose education,
revelation or a legislator. You’ll think otherwise only if you
wish to confuse it with civil laws in the absurd way thattheologians do.
The weapons of fanaticism may destroy those who upholdthese truths, but they’ll never destroy these truths themselves.

as plenty of experience lets us say that religion doesn’t imply
perfect honesty, that same experience entitles us to thinkthat atheism doesn’t preclude it!
Who knows after all whether the reason for man’s existence doesn’t lie in his existence itself? Perhaps he wasthrown by chance on a point of the earth’s surface without
knowing how or why, but knowing simply that he has to live
and die, like mushrooms that appear overnight or flowersthat grow beside ditches and cover walls.
Let’s not get bogged down in ·attempts to think about·infinity; we aren’t built to have the slightest idea of it; andwe’re absolutely incapable of tracing things back to their
origin. And it makes no difference to our peace of mind
whether matter is eternal or was created, whether there is
or isn’t a God. It is stupid to torture ourselves about things
that we can’t know and that wouldn’t make us any happier
if we did manage to know them.
I am told to read the works of the defenders of Christianity[and he names some]; but what will they teach me? Or rather,what have they taught me? There’s nothing to them but
boring repetitions by zealous writers who add to each other
only verbiage that is more apt to strengthen than undermine
the foundations of atheism. The arguments that peoplebase on the spectacle of nature aren’t made any stronger
by their sheer quantity: Either •the structure of one finger,
one ear, one eye or one of the observations of Malpighi [apioneer of microscopy] proves everything—proving it better than
Descartes and Malebranche do—or •none of this stuff proves
anything. It ought to be enough for deists, and even for
Christians, to point out that throughout the animal kingdom
a single purpose is achieved by an infinity of different means,
each of which fits the purpose precisely. [Deism differs fromThe existence of God
I am not questioning the existence of a supreme Being; onthe contrary, it seems to me extremely probable that there
is such a Being. But that doesn’t prove that some one cultmust be right, as against all the others; it is a theoretical
truth that serves very little practical purpose. So that, justtheism in (a) not appealing to revelation for knowledge of God’s existenceor nature, and/or (b) not attributing to God any continuing interest in19

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as the mind recovers. . . .its strength in the strength of thebody, it nearly always returns to its former opinions andacts accordingly). Anyway it is a lot more than is saidby the physician Diderot in his Philosophical Thoughts, ahigh-flying work that won’t convince any atheist. [Diderot

the created world and/or (c) not regarding God as having many personal

For what stronger weapons could one have toflatten the atheists? If my reason doesn’t deceive me, man
and the whole universe seem to have been destined for thissingle cluster of purposes. Everything—sun, air, water, theorganisation and form of bodies—is set out in the eye as
though in a mirror that faithfully presents to the imagination
the objects that are depicted there, in accordance with thelaws that are needed for the endless variety of bodies thatare used for seeing. We see everywhere ears of strikingly
different shapes—e.g. in man, animals, birds, fish—but thesedifferent constructions are used for one single end. All ears
are constructed in such a way that they are mathematicallyjust right for one single purpose, namely hearing. The deist
asks: ‘Would chance be a great enough mathematician toachieve this variety of means to a single end?’ He also points
to the parts of animals that are obviously there for future use:the butterfly in the caterpillar, man in the spermatozoon,
a whole polyp in each of its parts, the adult heart-valve
in the foetal structure that it grows from, the lung in the
foetus, teeth in the hollows from which they grow. . . . And
as deism’s supporters overlook nothing in their attempts
to justify it, tirelessly piling proof upon proof, they want totake advantage of everything, even the mind’s weaknesses incertain cases. ‘Look’, they say, ‘at the Spinozas, the Vaninis,
the des Barreaux, the Boindins—apostles ·of atheism· who
do more honour than harm to deism. Their unbelief only
lasted as long as their health did’; and the deists add
that atheists nearly always renounce atheism when •their
passions have weakened along with the body that is •theirinstrument.
qualities.]

wasn’t a physician though he did translate a large medical work. La
Mettrie was a physician.] What is to be said in reply to someone

who says [the quotation runs to the end of this paragraph]: ‘We don’tknow nature at all; causes hidden deep within her may haveproduced everything. Look for yourself at Trembley’s polyp!
[See page 23.] Doesn’t it contain inside it the causes of its own
regeneration? Then why would it be absurd to believe that
there exist physical causes for everything that has
been made, causes that govern and interlink thewhole series of events in this vast universe with suchnecessity that nothing that happens could have nothappened; that it is our absolutely incurable ignorance of these causes that has made us resort to aGod. . . .?
Thus, •destroying chance isn’t •proving the existence of asupreme Being, for there may be something that is neither
chance nor God—namely, nature, the study of which can
only produce unbelievers, as is shown by the way of thinkingof all its most successful observers.’
So the ‘weight of the Universe’ won’t bother the atheist,
let alone ‘crush’ him! [La Mettrie here quotes phrases from Diderot.]
All the endlessly recited signs of a Creator. . . ., however hard
they are pushed, are obvious only to anti-Pyrrhonians, i.e.
to those who have enough faith in their reason to think thatthey can judge on the strength of certain appearances; but,
as you can see, atheists can fight back with other absolutely
opposite appearances that may be just as strong.

That is certainly everything that can be said in favourof the existence of a God (though the last argument is
trifling, because such conversions are short-lived—as soon
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The law of natureof mine who is as free-swinging a Pyrrhonian as I am, aman of great worth who deserves a better fate. His reply
was very curious. ‘It is true’, he said, ‘that the cases forand against shouldn’t trouble the soul of a philosopher, whosees that •nothing is demonstrated clearly enough to force
agreement, and indeed that •the signs offered in supportof one side are immediately destroyed by ones presented insupport of the other. Yet’, he said, ‘the universe will never be
happy unless it is atheistic.’ Here are the reasons given by
this dreadful fellow [La Mettrie is of course joking, as with the words‘infected’ and ‘poison’ below.]. If atheism were generally accepted(he said), all the branches of religion would be destroyed, cut
off at the roots. No more theological wars, no more soldiersof religion—those dreadful soldiers! Nature, now infectedby sacred poison, would get back its rights and its purity.
Mortal men, deaf to all other voices, would calmly follow
only the spontaneous promptings of their own individual
being, which are the only ones that it is dangerous for us todisregard, the only ones that can lead us, along the pleasantpaths of virtue, to happiness.
Such is the law of nature: anyone who obeys it strictly isan honest fellow who deserves the confidence of the wholehuman race. If someone doesn’t follow it scrupulously, heis either a knave or a hypocrite, whom I distrust; he can’t
avoid that by conspicuously going through the motions of
belonging to some other religion.
After that let the light-minded populace think differently,
let them dare to claim that it’s dishonest not to believe inrevelation, that we need some religion—any religion—otherthan the religion of nature. How miserable! How pitiful! And
what a good opinion each person gives us of the religion hehas embraced! We aren’t trying here to seduce the rabble
into giving us their votes. ·We couldn’t get any votes fromthose people by using these arguments·. Anyone who erects

Listen to the naturalists again! They tell us that •the samecauses that enabled a chemist to create the first mirror bya chance mixture of certain materials are used by nature
to create clear water, which the simple shepherdess uses
for the same purpose; that •the movement that conserves
the world could have created it; that •each body occupies
the place assigned to it by its nature; that •the air had
to surround the earth for the same reason that iron andother metals are produced by its bowels; that •the sun is
as natural a product as that of electricity; that •it wasn’t
made to heat the earth and all its inhabitants (whom it
sometimes burns) any more than the rain was created inorder to make seeds germinate (which it often spoils); that•a mirror and water weren’t created to enable us to look at
ourselves in them, any more than was any polished bodywith the same property; and that •the eye is indeed a sort of
spy-hole through which the soul can contemplate the imagesof objects as they are represented to it by those bodies; butthat •there’s no proof that this organ was really created,or placed in its socket, specifically for that purpose; that
•Lucretius, Lamy and all past and present Epicureans might
be right when they ·reverse the explanatory order that thedeists and theists believe in, and· claim that the eye sees
only because it happens to be organised and placed as it is,and that the rules of motion that nature follows in generating
and developing bodies ensure that it wasn’t possible for thatwonderful organ to be organised and placed otherwise.
Those are the cases for and against—a summary of thegreat reasons that will always divide philosophers: I’m notchoosing a side. ‘It’s not in my power to decide so great acontroversy between you.’ [La Mettrie says this in a line of Latin
poetry, quoting Virgil.] That’s what I said to a French friend
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altars to superstition in his heart is constitutionally built toworship idols and not to care about virtue.
But since all the soul’s abilities depend so much on thespecific organisation of the brain and of the whole body that
obviously they are nothing but that very organisation, themachine is perfectly explained! ·Don’t try to fend off thisthesis by claiming that man is special, not like other animals·.
Suppose that man alone received the law of nature as his
heritage, so that he was alone among animals in having•that delicate conscience that is so easily wounded,•that ·capacity for· remorse that is no more foreign tomatter than thought is, and no doubt•other moral features as well,would that make him any less of a machine? ·Absolutely
not·! Those differences between man and the others could
be upshots of his having•a few wheels and springs more than the most perfect·non-human· animals have,•a brain proportionately closer to the heart and thus
receiving more blood,. . . .
•and perhaps—how do I know?—unknown causes.
Then would the machine’s organisation suffice to explain
everything? I’ll answer this again: Yes. Since thought
obviously develops with the organs, why shouldn’t the matterthat the organs are made of also be capable of remorse once
it has, in the course of time, become capable of feeling?
Thus ‘the soul’ is an empty term, with no idea associatedwith it; a good mind should use it only to refer to the part ofus that thinks. Given the slightest principlec of movement,[see note on page 12] animate bodies will have everything theyneed to move, feel, think, repent and (in brief) to conduct
themselves ·appropriately· in the physical realm and in the
moral realm that depends on it.
I’m not supposing anything. I am claiming that all the old

problems about matter, life, and mind have been definitively
solved. If you don’t yet believe this, here are some empirical
data that will completely satisfy you.

Self-moving body parts
1. All animal flesh palpitates after death, and the more
cold-blooded the animal is and the less it perspires, thelonger this goes on. Tortoises, lizards, snakes etc. bear thisout.
2. Muscles separated from the body contract when they
are pricked.
3. The bowels retain their peristaltic. . . .movement for along time ·after death·.
4. A simple injection of warm water reanimates the heart
and the muscles, according to Cowper.
5. A frog’s heart, particularly when left in some warm
place, moves for an hour or more after removal from the body.
If the movement seems to have vanished beyond recovery,
you only need to prick the heart and this hollow muscle
beats again. . . .
6. Francis Bacon, a first-class author, speaks in his
History of Life and Death of a man convicted of treason whoseheart was torn out while he was still alive, and thrown into
the flames; for seven or eight minutes this muscle jumped
up and down, first to a height of one and a half feet and thengradually tailing away.
7. Take the heart out of a chicken embryo and you’ll see
the same thing. . . . The warmth of one’s breath alone revives
an animal that is on the point of death in a pumped-out
vacuum flask.
Boyle and Steno have reported similar results with pigeons, dogs, rabbits, pieces of whose hearts move just likewhole hearts.. . . .
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8. Caterpillars, worms, spiders, flies and eels show moreof this same phenomenon, and the movement in the cut-off
parts increases in hot water because of the fire it contains.
9. A drunken soldier cut off the head of a turkey-cockwith a sabre. The animal stayed upright, then it walked,
then ran; when it ran into a wall it turned round, beat its
wings, and ran some more until it fell down. As it lay there
its muscles went on moving. I saw this myself; and one caneasily see more or less the same phenomena in kittens or
puppies whose heads have been cut off.
10. After polyps have been cut up, they don’t justmove; within eight days each piece generates a new animal!
I’m sorry for the naturalists’ theory of reproduction—well,actually, I am pleased, because this discovery ·about polyps·
teaches us never to draw general conclusions, even from themost abundant and decisive empirical evidence.
I have given many more facts than are needed to prove
beyond all doubt that each tiny part of an organic bodymoves according to its own principlec . And to prove thatthese movements don’t depend on the nerves, as voluntary
movements do, because they occur without the moving
part’s interacting causally with the circulation, ·i.e. withthe animal spirits that circulate through the nerves·. Now, if
this force can be observed even in fragmentary fibres thenit must also be present in the heart, which is a particularlycomplex structure of fibres. I didn’t need Bacon’s anecdote
to convince me of this. It was easy for me to deduce it from•the perfect structural likeness between human and animalhearts,. . . .and from •the fact that in corpses everything is
cold and flaccid. If executed criminals were dissected while
their bodies were still warm, the same movements would beseen in their hearts as are observed in the facial muscles of
decapitated people.
The principlec of motion in whole bodies or in chopped-up

parts of them is such as to produce movements that are notdisorderly as has been thought, but completely regular, bothin warm whole animals and in cold incomplete ones. My
opponents will have to resort to denying countless facts thatanyone can easily verify.
If I am now asked where in our bodies this innate force—·this principlec of motion·—resides, I reply that it is obviously
situated in what the Ancients called the parenchyma, i.e. thevery substance of the body-parts, excluding
the veins, arteries, nerves, in short, the entire body’s
organisation.
The result is that each part (·which may be too small to
include any aspect of the body’s organisation·) contains its
own ‘springs’, more or less strong ones depending on thatpart’s needs.

The ‘springs’ of the human machine[The link in English between ‘machine’ and ‘mechanical’ is pretty obvious;
in French it is even more so: machine, machinal.]

Let’s look in more detail at these springs of the humanmachine. All the body’s movements—
vital,
animal,natural, andautomatic
are carried out by them. Aren’t all these mechanical?
•the body draws back, struck with terror at the sightof an unexpected precipice,•the eyelids blink under the threat of a blow,•the pupils contract in bright light to protect the retina
and dilate to see objects in the dark.
And aren’t all these also mechanical?
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La Mettrie•the skin’s pores close in winter to keep the cold away

imagination.

from the blood-vessels,•the stomach heaves when upset by poison, by a little
opium or by any emetic, etc.,•the heart, the arteries and the muscles contract during sleep just as they do when the person is awake,•the lungs unceasingly do their job as an active bellows.

But in order not to become bogged down in profusion ofpoorly understood details, I’ll have to limit myself to a few
questions and reflections.
Why does the sight, or the mere idea, of a beautiful
woman cause special movements and desires in us? What
happens then in certain organs—does it come from the very
nature of those organs? Not at all! It comes from theinterplay between those muscles and the imagination. [He

And aren’t these mechanical as well?
•all the sphincters of the bladder, the rectum, etc. dotheir work,•the heart beats, contracting more strongly than any
other muscle,•the erector muscles make a man’s penis go erect, likethat of an animal that masturbates, and even of achild, who can have an erection when that part is
stimulated.

also calls this interplay ‘a sort of sympathie’, using this word in its earlymodern sense in which it refers to a kind of causal copying, echoing, or
the like; as when by playing an open-string G on one violin starts a slight
trembling in the G-string of another nearby violin.] All we have here

is one spring that is •set going by the sight of beauty and•arouses another spring that was sound asleep until theimagination awoke it. And how can this happen if it isn’t due
to the chaotic tumult of the blood and spirits, moving withastonishing speed and swelling the hollowed-out organs?

The last example, incidentally, shows that the penis has a
special kind of ‘spring’ that isn’t yet understood, producing
effects that haven’t yet been well explained despite all our
knowledge of anatomy.

Since there is obviously causal interplay between motherand ·unborn· child7 , and since it is hard to deny the facts
reported by Tulpius and by other equally trustworthy writers. . . ., we believe that that is how the foetus feels the effectof its mother’s impetuous imagination, as soft wax receives
all sorts of impressions, and that the mother’s desires can be
imprinted on the foetus in a way that we don’t understand. . . .
In saying this I am making amends to Malebranche, ·who
accepted this theory, and· who was excessively mocked forhis ‘credulity’ by authors who hadn’t observed nature closely
enough and wanted to subject it to their ideas.

I shan’t spend any longer on all these subordinate little
springs that everyone knows. But there is another more
subtle and wonderful one, which drives them all. It is thesource of all our feelings, all our pleasures, all our passions
and all our thoughts; for the brain has muscles for thinking
as the legs do for walking. I am talking about the instigating
and impetuous principlec the soul [he gives the Greek word thatwas Hippocrates’ name for it]. This principlec exists and is locatedin the brain at the starting-point of the nerves, through which
it exerts its control over all the rest of the body. [See note on
page 12 regarding ‘principlec ’.] This explains everything that canbe explained, even the surprising effects of diseases of the7

Look at the portrait of the famous Alexander Pope, theEnglish Voltaire. The efforts and strains of his genius are
etched in his face. It is totally convulsed, his eyes are

At least through the blood-vessels. Mightn’t there also be some through the nerves?

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La Mettriestarting out of their sockets and his eyebrows are liftedby the muscles in his forehead. Why? Because the root of
his nervous system is in labour and his entire body is boundto feel the effects of such a difficult birth. Where would
all these phenomena come from if there weren’t an internal
string pulling on the outer ones? To bring a soul into the
explanation of them is to be reduced to the intervention of
the Holy Ghost!
For if what thinks in my brain is not a part of that organ
and thus of the whole body, why, when I am lying calmly in
my bed planning a book or conducting an abstract line ofreasoning, does my blood begin to race? Why is my mind’s
fever transmitted to my veins? With that question in mind,
look at men of imagination, at great poets, at men who areenchanted by a well-expressed feeling or who are bowled overby. . . .the charms of nature, of truth or of virtue! By their
enthusiasm, and by what they tell you they have felt, you’ll
judge the cause by its effects. From the harmony ·between
the inner life and the outer· you will discover the material
unity of man. (·Of course ‘harmony’ was made famous inthis context by Leibniz; but· a single anatomist, Borelli, wasbetter acquainted than any Leibnizian with the harmony·that unites a man·. Think about it: if•the tautness in the nerves that produces pain causes
the fever that disturbs the mind and saps its will; ifconversely•an overactive mind disturbs the body and lights thefire of consumption [= tuberculosis] that carried off Bayleat such an early age; if•some ·external· stimulus makes me want—forces me
to desire ardently—something that I didn’t care about
the moment before; and if•in turn brain-events stir up the same lust and thesame desires,

why divide into two what is obviously only one? ‘But what
about the power of the will?’ That leads nowhere. The will
·does indeed issue commands, but it· •receives and mustobey a hundred commands for every one that it •gives. Whenthe body is in its healthy state, it obeys because a torrent ofblood and spirits force it to do so, because the will has as
its executives an invisible legion of fluids that move fasterthan light and are always ready to do its bidding; what amarvel all this is! But just as the nerves exercise this power,
they also thwart it. Can the best will and the most violent
desires of an exhausted lover bring back his lost energy?
Alas, no, and his will is the first to be punished because incertain conditions he can’t help wanting pleasure. What I
said before about paralysis etc. is also relevant here.
You’re surprised by jaundice! Don’t you know that bodies’
colours depend on the colours of the lenses through which
we look at them! Don’t you realize that the hue of objects
is that of the ·bodily· humours (at least for us, the helplessplaythings of a thousand illusions). [Re ‘humours’, see page 3.]
But remove that ·yellow· hue of the eye’s aqueous humour
and make the bile flow through its natural filter, and the soul
will have new eyes and will stop seeing yellow. Isn’t sightrestored to the blind by removing a cataract? and hearing to
the deaf by clearing out the Eustachian tube?. . . . Our lovely
soul! and our powerful will that •can’t do a thing unless the
body’s disposition allows it to, and that •changes its tastes
with age and fever! It’s not surprising that philosophers
have always aimed at bodily health as a way to preserve
the health of the soul. . . . The diet that suits the bodyis always the one that reasonable physicians say shouldcome first if we want to educate the mind and to raise it
to a knowledge of truth and virtue, which are only empty
sounds amid the disorder of diseases and the uproar of thesenses! Without the rules for maintaining good bodily health,25

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Epictetus, Socrates, Plato and the rest would be preachingin vain: moral teaching won’t do any good for someone who
isn’t endowed with sobriety, the source of all the virtues, asintemperance is the source of all the vices.

chyle first comes into the blood, nature’s first concern is tostimulate in it a sort of fever (the chemists, who are obsessedby furnaces, had to take it as a sort of fermentation!). This
fever speeds the ·animal· spirits on their way; and they thenmechanically stimulate the muscles and the heart as though
they were sent there on the orders of the will.
Those, then, are the causes of life, the life-forces, which
through a hundred years keep the body’s solids and fluids
in the perpetual motion that they require. [A hundred years?

More about the organisation of the human body
What more is needed. . . .to prove that man is only an animal,
i.e. a system of springs that wind each other up without ourbeing able to say at which point on the human circle naturebegan? These springs differ from one another—if at all—onlyin their locations and in their force, and never in their nature.
So the soul is only a principlec of motion, a tangible materialpart of the brain that we can safely consider as a mainspringof the whole machine, which visibly influences all the othersprings and seems indeed to have been made first; in whichcase all the others are a mere by-product of it. We’ll see thisthrough some reports I’ll make of observations concerning
various embryos. [La Mettrie uses the word émanation, rather roughly

Perhaps La Mettrie thought that this would be a normal lifespan if people
had reasonable luck and lived healthy lives. On page 25 he speaks ofBayle’s having been killed by TB at ‘an early age’; Bayle lived to be 59
years old, a fairly late age by 17th century standards.] Do the solids

contribute more to this activity than the fluids, or less? Whoknows? All we do know is that the solids would soon grind
to a halt without the help from the fluids. The liquids act on
the vessels through which they circulate, jolting them into
becoming and remaining elastic. That is why the natural
spring of each substance ·in the body· is still more or lessstrong, according to the remaining vestiges of life; the springis the last thing to die. So it is very true that •this strength
in the animal parts can be preserved and increased by thestrength of the circulation; but •it doesn’t depend on thecirculation, because, as we have seen, it doesn’t even need
the member or organ to be whole!
Yes, I know that this opinion hasn’t been well received by
all scientists, and that Stahl above all had only contempt for
it. That great chemist wanted to persuade us that the soulalone was the cause of all our movements; but that is thetalk of a fanatic, not a philosopher.
Efforts have already been made to destroy Stahl’s hypothesis, but there is no need for that. All we need is to glance
at a violinist. What suppleness! What nimble fingers! His
movements are so rapid that they hardly seem to be strungtranslated here by ‘by-product’. The word was mostly used for theologicaland metaphysical purposes that he scorned, and his selection of it wasprobably meant ironically.]

A special feature of our machine is that every fibre in
it, right down to the smallest, oscillates, and this natural
oscillation is like that of a clock—it sometimes winds down.
It must be renewed when it dies down, strengthened whenit grows feeble, and weakened when it is oppressed by too
much strength and vigour. That is what constitutes the only
true medicine.
[The word ‘chyle’ in this paragraph—it’s the same word in French—refers to a kind of material in the digestive system which is caused by theintake of food and causes various life-processes in the body.] The body

is nothing but a clock whose horloger [= ‘someone who makes orrepairs and maintains clocks’] is newly formed chyle. When the26

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out in time. So I challenge the Stahlians—those experts on
everything that our soul can do—to tell me how the soul
could possibly carry out so rapidly so many movements in somany different places so far away from it. It is like supposing
a flautist who could play brilliant cadenzas on countlessholes that he doesn’t know and can’t even put his fingers on.
. . . .But perhaps Stahl was even more blessed by nature•as a man than •as a chemist and ·medical· practitioner—
why not? Perhaps he (the lucky mortal!) was endowed witha different soul from other men; a sovereign soul which, notcontent with having some control over the voluntary muscles,
had no trouble holding the reins of all the body’s movements
and could suspend, calm or arouse them at will! With such a
despotic mistress—controlling the heartbeat and the laws ofcirculation—there would doubtless be no fever, no pain, noloss of energy, and no shameful impotence or embarrassing
erections. The soul decrees and the springs act, tighten, or
relax. How could the springs of Stahl’s machine have broken
down so soon? [He lived to the age of 73.] With such a great
doctor in residence one should be immortal.
However, Stahl wasn’t alone in rejecting the principle ofthe oscillation of organic bodies. Greater minds than his did
without it when trying to explain the heart’s movement, theerection of the penis, etc. One has only to read Boerhaave’s
Institutions of Medicine to see what laborious and seductive
systems that great man was forced to give birth to with thesweat of his great genius because he wouldn’t credit theheart with such striking power.
Willis and Perrault were lesser minds ·than •Boerhaave·
but were careful observers of nature. (The famous •Professor
from Leiden got most of his knowledge of nature secondhand, from the writings of others.) They seem to haverejected the principlec that I am discussing, in favour ofa soul generally spread throughout the body. But in their

hypothesis—which Virgil and all the Epicureans had before
them, and which seems at first sight to get support fromthe facts about polyp—the movements that survive after
the death of the animal come from a remnant of the soul,preserved in the parts that contract although they’re nolonger stimulated by the blood and the spirits. From this we
can see that these writers, whose works are much better than
all the fables of philosophy, were mistaken only in expressing
themselves badly, using obscure and meaningless terms.
(The same trouble as with writers who credited matter withthe power of thought!) For what is this remnant of the soul
but the Leibnizians’ ‘motive force’? That was a bad label forit, but Perrault in particular really had an idea of it. See his
Animal Mechanics.

Feeling and thought
Now that it has been clearly demonstrated—against the
Cartesians, the Stahlians, the Malebranchians and (though
they hardly deserve a mention here) the theologians—that
matter moves by itself, not only when it is organised(as in a whole heart, for example). but even when thatorganisation is destroyed,
human curiosity would like to know how a body’s being
initially endowed with a mere •breath of life leads to its being
graced with •a capacity for feeling and even •for thinking.
And to satisfy this curiosity, good God, what efforts have been
made by some philosophers! And what rubbishy nonsense I
have been patient enough to read on this subject!
Experience teaches us only this:If one or more fibres still have some movement, however little, it takes only a jab for this barely existent
movement to be kicked back into life.
27

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Solving two ‘riddles’

This can be seen in the host of empirical facts that I haveadduced to disprove various systems. This is a constant:movement and feeling take turns in arousing each other,both in intact bodies and in those same bodies when theirstructure is destroyed; not to mention certain plants thatseem to exhibit the same symptoms of feeling and movement
combined.

If you’ll just grant me that•organised matter is endowed with a motive principlec ,which is the only thing distinguishing it from unorganised matter (come on now! can you refuse ·to accept·
the most incontrovertible observations?); and that•everything that happens in animals—·and everythingthat makes one animal unlike another·—arises fromdifferences in how they are organised (and I have
proved that well enough);I can solve the riddle of substances, and the riddle of man.
It turns out that there is only one of them in the universe,
and that man is the most perfect one. [In that sentence, ‘one

But in addition, many excellent philosophers have demonstrated that •thought is only a capacity to •feel, and thatthe rational soul is merely the sensitive soul when it iscontemplating ideas and reasoning! This is proved by thesimple fact that when feeling is lost thought is lost also, as
in apoplexy, lethargy, catalepsy, etc. ‘The soul thinks just as
much during comas, despite not remembering the ideas it
has had’—what a ridiculous claim!

of them’ must mean ‘one ’substance’, and ‘the most perfect one’ has tomean ‘the most perfect substance’. We’ll see on page 33 that La Mettrie

Concerning this development, it is folly to waste one’s
time trying to discover its mechanism. We don’t know whatmovement really is, any more than we know what matterreally is. There’s no way of discovering how matter comesto move unless, like the author of The Natural History of
the Soul, we revive the ancient incomprehensible doctrine ofsubstantial forms! [The author in question is La Mettrie himself; hisreally does think that the entire material universe constitutes a single
substance; so presumably he means here that man is the most perfectportion of substance.] Man is to the apes (the cleverest animals)
what Huygens’s planetary clock is to one of Julien Leroy’s
watches. It took more instruments, more wheel-assemblies,
more springs to show the movement of the planets thanto show or announce the time; it took ·the mechanicalmodel-maker· Vaucanson more skill to make his •flautist
than his •duck; ·and now we can extend this line of thought
further·: Vaucanson would have needed even more skill tomake a ·mechanical· •speaker; but we can’t go on regarding
a talking machine as impossible, particularly at the handsof a new Prometheus. Continuing the line of thought: nature used more skill and more apparatus to construct andmaintain a machine that could continue through a whole
century marking all the ‘beats’ of the heart and the mind.
We can’t tell the time from the pulse, but it is at least thebarometer of heat and liveliness, from which we can judge

Natural History of the Soul was published a year before Man—Machine.
During that short interim he became impatient and dismissive of various
parts of the earlier work, including its tolerant treatment of ‘substantial
forms’ and—as we shall see soon—its hostility to the thesis that animals

So I am as reconciled to not •knowing how
inert simple matter comes to be active and organised as I
am to not •being able to look at the sun except through a
red lens. And I am equally at peace about nature’s otherincomprehensible wonders, about the production of feelingand thought in a being which in the past seemed to ourlimited sight to be a mere lump of clay.
are machines.]28

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the nature of the soul, ·this being abstractly comparablewith judging what the time is by looking at a clock·. I am
not mistaken; the human body is a clock, a huge andcomplex and finely designed clock. How well designed? Well,
if the cog-wheel that marks the seconds happens to stop,
the one that marks the minutes goes on turning, as does
the wheel marking the quarter-hours; and similarly withthe others, when the first ones are halted by rust or someother cause. For we know—don’t we?—that when several·blood·-vessels are blocked, that doesn’t stop or suspend themain movement in the heart, which is like the mainspringof the machine. . . . And we know—don’t we?—that when
the optical nerve is compressed and no longer lets throughthe images of objects, this loss of •sight doesn’t spread tointerfere with •hearing, any more than the loss of hearing,
through the failure of the relevant nerve, involves the lossof sight. Similarly, we know that someone in an epileptic
seizure can •hear without being able (for a while) to •say that
he can hear; and a deaf person can have his language-nerves
in good order so that he mechanically reports all the dreams
that come into his mind. Such phenomena don’t surprise
enlightened physicians, who know what to expect from man’snature. Incidentally, of any two doctors the better and moretrustworthy will always be, in my opinion, the one •whoknows more about. . . .the mechanics of the human body and•who walks away from ‘the soul’ and all the upsets that thisfigment of the imagination causes in fools and ignoramuses,and •who concentrates solely on pur naturalisme [= roughly‘on the plain empirical facts’].

all respects if, born in an age that he didn’t need to enlighten,
he had understood •the value of experiment and observationand •the danger of straying from them. But it is just as fair
for me to make true amends here to that great man for all
those petty philosophers who make bad jokes and mimic
Locke and who, instead of laughing impudently in Descartes’
face, would have done better to realise that without him thefield of philosophy might perhaps still be waste land, like thefield of right thinking without Newton.
No-one denies that this famous philosopher made many
mistakes; but he understood animal nature, and was thefirst to demonstrate perfectly that animals were mere machines. After such an important discovery, requiring somuch wisdom, it would be ungrateful of us not to pardon all
his errors!
I see the errors as compensated for by that great admission. Descartes goes on and on about the distinction
between the two ·kinds of· substances, but it’s obvious that
this was only a trick, a stylistic device to get the theologians
to swallow the poison—·poison for them, that is·—hidden
behind an analogy which everyone is struck by except for
the theologians who can’t see it at all. ·I am talking about
the analogy—the great over-all similarity—between men andthe other animals·. It’s that, it’s that strong analogy, thatforces all scholars and true judges to admit that men—those haughty, vain, self-praising beings who aremarked off by their pride more than by the label ‘men’—are basically only animals and upright-crawling machines.
They all have that wonderful instinct which education transforms into intelligence. It is located in the brain or, when thebrain is missing or ossified, in the brain-stem; never in the
cerebellum [and he gives a reference for evidence for this].

So let the writer calling himself Charp make fun of philosophers who have considered animals to be machines. How
different is my opinion! [‘Charp’ was the pseudonym under which La
Mettrie published his Natural History of the Soul; see note on page 28.] I
believe that Descartes would have been an admirable man in29

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There is nothing contradictory about(1) being a machine and (2) being able to feel, to think
and to tell right from wrong like telling blue fromyellow; that is,(1) being a mere animal and (2) being born with intelligence and a sure instinct for morality,
any more than there is about•being an ape or a parrot and •being able to giveoneself pleasure.
. . . .Who would ever have guessed in advance that a drop of
liquid ejaculated in mating would give rise to such divine
pleasure? or that there would be born from it a little creature
who would be able one day, given certain laws, to enjoy
the same delights? Thought incompatible with organised
matter? That is so far from right, I believe, that thought
seems to be a property of matter, like electricity, power to
move, impenetrability, extension, etc. [La Mettrie is here using

been hesitant to accept this. [In that sentence, ‘curious’ translatescurieux. which can also mean ‘careful’, painstaking’.] As each drop ofsemen contains an infinity of these little worms at the startof the journey towards the ovary, only the most skilful or the
sturdiest has the strength to penetrate the ovary and implant
itself in the egg provided by the woman, which provides its
first food. Sometimes a little worm ·doesn’t have to get into
the ovary because it· catches an egg in the Fallopian •tubes;
and this egg is carried by these •canals to the womb, where
it takes root like a grain of wheat in the ground. It grows
enormously through the next nine months; but it is likethe eggs of other females—·and like the other eggs of thissame female·—except for its skin (the ‘amnion’), which neverhardens, and dilates tremendously. You can tell that thisis so if you compare a foetus found in place and ready tohatch with other little embryos that have hardly started. (Ionce had the satisfaction of seeing this for myself in ·thewomb of· a woman who had died just before giving birth.)·The comparison is easy to make·, because at that time thetiny animal—which is imprisoned in the amnion and trying
automatically to see the light of day—breaks out by pushingits head against this membrane, like a chick emerging fromits egg. Something that I haven’t seen pointed out anywhere
else is this: the enormous stretching of the amnion doesn’t
make it any thinner. In this it is like the womb, whose very
substance swells up with infiltrated fluids, independently of
how far its vessels are filled up and spread out.
Let us look at man inside and outside his shell. Let’s
examine the youngest embryos—four, six, eight or fifteendays old—under a microscope, after which we can do it with
the naked eye. What do we see? Only the head: a little roundegg with two black dots that indicate the eyes. Before that,when everything is more formless, we can see only a pulp
which is‘property’ in a traditional sense in which a ‘property’ of a thing of kind K
is a quality that (a) is not included in the essence or definition of K but
nevertheless (b) must be possessed by everything of kind K. It somehow•follows from K’s essence but isn’t •included in K’s essence.]

Do you want some more empirical facts? Here are someunanswerable ones, all showing that man is exactly likeanimals both in his origin and in every respect that I havetaken to be essential to the comparison between them.

From sperm to man
I appeal to the good faith of our observers. Isn’t it true thata man starts off as a worm that becomes a man just as acaterpillar becomes a butterfly? The most serious authors[he names one] have told us how to go about seeing this little
animal. All curious observers [he names one] have seen it in
the man’s semen and not in the woman’s; only fools have30

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though it were an impenetrable mystery. ·In the next
paragraph I give an example of such a blank wall·.
It so seldom happens that in intercourse the partners’
seminal fluids actually meet that I’m tempted to think thatthe woman’s fluid has no role in reproduction, ·which would
clash nastily with the theory that development is all a matterof the coming together of bodily parts·. ·Objection to thisthought·: How can we explain the facts of reproduction
without help from the handy coming-together-of-parts, which
accounts so well for the fact that children sometimes resemble their father and sometimes their mother? ·Reply to that
objection·: Should the fact that we are in trouble with an
explanation be allowed to outweigh facts? It seems to me
that ·in copulation· the male does everything, whether he’s
doing it in a sleeping woman or in one who is eagerly sexually
involved. And if that is right, then the development of theembryo could be fixed for eternity in the seed, the little worm,of the man. But all this is far beyond the reach of even thebest observers. Not being able to get a grip on any of this,they can’t judge what the mechanism is by which bodies are
created and develop, any more than a mole can judge how
far a deer can run.

•the brain, in which are formed from the outset theorigin of the nerves, i.e. the source of feeling, and•the heart, which already in this pulp is able to beat.
This embryonic heart. . . .may already owe part of its
liveliness to the influence of the nerves.
Then we see the head pushing out a gradually lengthening
stem, which opens up to form first •the thorax, in which
the heart has come down and settled, and then •the belly,
which is separated ·from the thorax· by a dividing wall (thediaphragm). These two cavities produce further features:
one of them yields the arms, hands, fingers and hairs; theother yields the thighs, legs, feet, etc.; the only difference weknow of ·between arms etc. and legs etc.· is their differenceof position, which fits them to balance or support the body.
It—·the entire development of the embryo·—is a striking
example of vegetative growth! ·Don’t write off the comparison
with plants as absurd·. The hair that covers the tops of ourheads corresponds to leaves and flowers of plants. Nature’s
luxuriance shines out everywhere. . . .
Nature is so uniform that we start to get a sense of
the analogy between the animal and vegetable kingdoms,
between man and plant. Are there perhaps animal plants,
i.e. plants that grow in the vegetable manner but also fight
like polyps or do other things that are specific to animals?
So there you have just about everything that is known
about reproduction. Some great men have said this:What leads to the formation of the eyes, the heart, thestomach and finally the whole body is the fact thatbody-parts attract each other, and are caused by theirown natures to join together and to occupy such andsuch places.
They may be right. But experience deserts us in the middle ofthese subtle inquiries, so I’m not going to make any guesses,
and will treat anything that my senses don’t perceive as

Reconciling ourselves to our ignorance
We’re real moles in the field of nature; our range is hardly
bigger than a mole’s; and when we put limits on things that
don’t have any, that is our pride speaking. Our situation is
like that of a watch. . . .that said:‘What! Was I made by that stupid workman? I who
can divide up time, I who can mark so exactly the
sun’s course, I who can call out the hours that I
mark? No, that’s impossible.’31

Man—Machine

La MettrieWe, ungrateful wretches that we are, similarly despise ‘thecommon mother of all the kingdoms’ as the alchemists callher. We owe her everything; she really has in an inconceivable way created everything; but we imagine—or rather wepostulate—a cause that is higher than her. [French doesn’t

ours is, and immortal if ours is; the two kinds of soul must
suffer the same fate, whatever that may be. So you haveescaped out of frying pan into the fire!
Break the chains of your prejudices and arm yourself
with the flaming torch of experience, and then you’ll honour
nature in the way it deserves, instead of drawing derogatory
conclusions from the ignorance in which it has left you.
Just open your eyes, and when there is something you don’t
understand, let it go. Then you will see that a labourer whose
mind and knowledge don’t stretch beyond the edges of his
furrow is not essentially different from the greatest genius, as
would have been shown by dissecting the brains of Descartes
and Newton; you will be convinced that imbeciles and idiots
are animals in human form, just as a clever ape is a little
man in another form; and ·you’ll be convinced· that, since
everything depends absolutely on differences in organisation,a well-constructed animal who has learnt astronomy can
predict an eclipse, and one who has exposed his intellectand good eyesight to what he could learn at the school of
Hippocrates and at patients’ bedsides can predict recovery
or death. It is through this sequence of observations andtruths that matter comes to have the admirable property ofthought joined to it, though we can’t see how they are joined
because the subject of this attribute is essentially unknown
to us.
I am not saying that every machine, or every animal,
perishes completely or takes on another form after death—I
don’t know anything about that. But to insist that an
immortal machine is a fantasy or a ‘being of reason’ is toreason absurdly; as absurd it would be for a caterpillar
to see the remains of its fellow caterpillars and lament
bitterly the fate of its apparently dying species. The soulof this caterpillar (yes, every animal has one) is too limited
to understand the changes of form that nature brings about.

distinguish personal from impersonal pronouns; but in this paragraph‘she’ seems right for Nature, given La Mettrie’s mother metaphor. Anyway,
his topic here is nature, or matter; you’ll see that he outright equatesthese.] No, there’s nothing low about matter—only crude eyes

see its most brilliant productions and don’t recognize that it’smatter that is at work in them; ·and those productions areindeed brilliant, for· nature is not a worker of limited ability.
She produces millions of men with more ease and pleasurethan a watchmaker has in creating the most complicatedof watches. Her power shines out as clearly in the creationof the lowest insect as in that of the most splendid man;she doesn’t put more effort into the animal than into thevegetable kingdom, or more into the finest intellect than into
an ear of corn. So we should •judge what is hidden fromour view and our researches on the basis of what we cansee; and we shouldn’t push the limits out further by our•imaginations. Observe the behaviour of the ape, the beaver,
the elephant, etc. If it’s clear that they couldn’t act as they
do without intelligence, why should we deny that they haveit? And if you agree that they have a soul—I’m talking to
you fanatics!—you have lost the argument. You may want toprotest:·We haven’t conceded much·. We have said nothing
about the nature of the animal soul, but now we dosay something, namely that it is mortal, ·unlike thehuman soul·.
But anyone can see that that’s an arbitrary statement [meaning something like: . . . that you are just making this up as you go along].
It is obvious anyone that the animal soul must be mortal if
32

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Even the cleverest of them could never have imagined that
it was to become a butterfly! It’s the same with us. Do weknow any more about our fate than about our origin? So let
us give ourselves over to incurable ignorance, on which ourhappiness depends. [In the French text it is clear that our happiness

ignores the grumblings of his vanity and is convinced that
he is only a machine, i.e. an animal, and he won’t ill-treat
his fellows; he knows too much about the nature of their·bad· behaviour. . . .
. . . dontl’inhumanité est toujours proportionée au degré d’Analogie
prouvée ci-devant.
literally translated: . . . the inhumanity of which is always
proportional to the degree of analogy proved above.
meaning: . . . ??.

what La Mettrie writes about that behaviour:

depends on our ignorance, not on our acceptance of it.]

The moral advantages of La Mettrie’s view of man
Anyone who thinks in this way will be wise, just, calm
about his fate and consequently happy. He will wait forhis death without fearing it or wanting it; cherishing lifeand finding it almost unintelligible that someone’s heart
might be corrupted by dislike of this delightful place; he’ll
be full of respect for •Nature; full of gratitude, affection
and tenderness in proportion to. . . .the kindnesses •she has
shown to him, happy to sense her ·within himself· and to
be present at the enchanting Theatre of the Universe. He
will certainly never destroy nature in himself or in anyoneelse. More than that: he will be full of humanity and will lovethe sign of it even in his enemies. [This means that he will love

Following the law of nature given to all animals, he doesn’twant to do to others what he wouldn’t like others to do tohim.
Let us then conclude boldly that man is a machine andthat the whole universe contains only one substance. . .
end of sentence: diversement modifiée.
literally translated: variously modified.
the point La Mettrie is making: The material world is justone big lump of stuff. We can mark off parts of it, but all thatdifferentiates one part from another is their having different
qualities, different •‘modes’; so they should be thought of as
basically not material things but just regions of the one stuff
that happen to be •‘modified’ in ways that differentiate eachfrom the surrounding regions.

whatever-it-is about others that shows them to be human, not . . . thatshows them to be humane ]. Look at how he will treat others. He

will pity the wicked without hating them; he’ll think of themas merely men whose construction was bungled. But his
pardon for the defects in the construction of their minds andbodies won’t detract from his admiration for such beauties
and virtues as they have. Those whom Nature has favoured
will seem to him more worthy of respect than those whom
she has treated as a wicked stepmother would. Thus wehave seen that the materialist in his thought and speech will
do homage to something that others quite wrongly refuse tohonour, namely the •natural gifts that people have, which
are the source of all their •acquired ones. The materialist

This is not a hypothesis built up using questions and suppositions; it is not the work of preconceived opinions of mine. It
isn’t even the work of my unaided reason: I regard reason asa very uncertain guide, and I wouldn’t have been willing tofollow it if the way hadn’t been lit up for us by the torch (soto speak) of my senses. That is what happened: experiencespoke to me in reason’s favour, so I worked with them incombination.

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Man—Machine

La Mettrie

But you must have seen that I have allowed myself todraw conclusions—always through the most rigorous andimmediate reasoning—only from a multitude of physicalobservations that no well-trained and informed person willquestion. And those are the only people I accept as judgesof the conclusions that I draw from these ·observations·;
I disqualify any man who is full of his own opinions but
isn’t an anatomist or educated in the only branch of sciencethat is relevant here, namely the study of the human body.
What could the weak reeds of theology, metaphysics andthe Aristotelian philosophy departments do against such afirm and solid oak? Those reeds are childish weapons, likepractice foils that can give pleasure in fencing but can neverwound an opponent. ·‘Weak reeds’?· Do I need to explain thatI’m talking about the empty, trivial ideas and the overused,pathetic reasoning about the supposed incompatibility of two
substances that incessantly touch and move each other andwill go on doing so as long as there remains the shadow ofa prejudice or of superstition on earth? Here is •my system,or rather •the truth, unless I’m greatly mistaken. It is shortand simple. If anyone wants to argue ·against it· now, letthem!

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