# Popular Science Monthly/Volume 10/April 1877/The First Popular Scientific Treatise

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* THE FIRST POPULAR SCIENTIFIC TREATISE.
By Professor S. P. LANGLEY,
OF THE ALLEGHENY OBSERVATORY.
SOME one has said that there is nothing in all the world of common places which was not once a novelty, and born from the conception of an original mind. The idea that science is not for the professional student only, but that every one will take an interest in Us results if they are only put before the world in the right way—this notion which has now produced a literature of its own—even ​this idea was once brand-new. At the present time, when the most recondite investigation is summarized and explained for the unscientific, so that what is capable of translation into common speech is discussed at tea-tables within a week after presentation, it is not easy to go back in imagination to a day when the student of Nature worked only for, and was judged only by, a narrow circle of his own, and most gentlemen and gentlewomen were not only completely ignorant of scientific thought and method, but would have felt in danger of acquiring pedantry in learning them. Such, however, was the state of things two hundred years ago in the then most cultivated society of Europe; and it was to Bernard le Bovier de Fontenelle that first presented itself the audaciously novel conception of writing a book which should render some of the results of science into a language comprehensible by the most fashionably ignorant, and in a style which should make science itself recognized as a permissible topic of discussion in the salons.
His happy thought was executed with a cleverness akin to genius: the book went into all languages, and is said to have been reprinted a hundred times during the last century. "Conversations on the Plurality of Worlds" was its title; and though it is by no means rare, and indeed remains a classic in its kind, it is probably nowadays known only by name to the majority of English readers. Yet, in its way, nothing better has been done since, or rather its way is one which has had no entirely successful imitator among all its numerous progeny. It will be interesting, then, to look at this original in a path since so well trodden, and in doing so it may be premised that the book appeared in 1686, and was addressed to such a circle of readers as then only French society and the court of Louis XIV. could furnish. The age of Corneille, Molière, and Racine, La Bruyère, La Rochefoucauld, and St. Simon, Bossuet, Massillon, and Bourdaloue (and it might be added of Fontenelle himself), was certainly not devoid of literary culture, and yet that very culture had so completely excluded science that we shall presently see the marchioness, who is presented to us as a type of accomplished elegance, expressing complete astonishment at hearing that the earth turns round, and the most naïve wonder at the idea that her park and castle, and she herself, are actually turning too!
The "Conversations" are introduced with a description of a moonlight night in the park, where the author is walking with the marchioness, to whom he is paying his court, with the accompaniment of perpetual and somewhat insipid compliment, which seems to have been a part of the conversational dress of the time, and to have belonged to the fashion of the period as much as its lace-covered waistcoats.
The talk is first of the beauty of the night, and moves on in an easy and natural tone, till the author casually speaks of the stars they are contemplating as "these worlds." The lady asks for an ​explanation, and, on being told that it is likely to prove too learned to amuse her, only insists the more on the perfect capacity of her sex for the reception of the most philosophic ideas, and demands a lesson on the stars at once.
"No!" replies Fontenelle, "never shall it he said of me that in a wood, at ten o'clock at night, I talked philosophy to the most charming person of my acquaintance. Seek your philosophers elsewhere!"
But it is vain for him to try to bring the conversation back to its former channel, and to represent how much better it would be to talk nonsense, "as any reasonable people would do in our place"—he has to yield; but the dialogue, often very lively, is represented through the book as carried on by the gentleman with the wish to pay his court under cover of talking science; while the lady is ever on the alert to call him back to his ostensible theme when she finds him trying to wander from it. We must perforce omit this in giving only a part, and that chiefly Fontenelle's; but even in teaching he will be found anything but dull. As his pupil is as ignorant as she is intelligent, he begins at the beginning:
"All philosophy, I said, is founded on two facts, that we have curious minds and poor eyes, for if your eyes were better you might see for yourself if the stars were suns lighting other worlds, or if, on the other hand, you felt less curiosity, you would not care to learn, which would come to the same thing; but everybody wants to know more than he can see, and there is the difficulty. If we could even see unmistakably what we see at all, that would be something gained, but we see quite wrongly, and so your true philosophers pass their lives in the unenviable condition of doubting what they do see, and trying to divine what they cannot. I always think of Nature as a great spectacle, something like the opera. From your opera-box you do not see the theatre quite as it really is, for the scenes and stage-apparatus are arranged for effect at a distance, and they keep the weights and wheels which put all in motion out of your sight. Naturally, you do not pay much attention to the principle on which all this works. But then, again, there may be a machinist down by the orchestra, who is puzzled by some stage-flight, which is unaccountable to him, and who feels that he must find out how it was done.
"The machinist, you observe, is something like the philosophers; but what makes the difficulty worse for them is, that in Nature's machines the cords are all hidden—hidden so neatly that people were a long time conjecturing as to what caused the movements of the universe. Just imagine, for instance, Pythagoras, and your Platos and Aristotles, at the opera—they and all their kind whose names are in such reputation. Suppose that they saw the representation of Phaethon borne off by the winds, that they could not discover the cords, and did not know what lay behind the scenes. One of them" (the author is here giving us samples of the philosophy still current ​in his time) "says, 'Phaethon is carried up by a hidden principle;' another, 'Phaethon is composed of certain numbers which make him rise;' another, 'Phaethon has a certain attraction toward the top of the theatre;' and a hundred such vagaries, which I should have supposed would have cost antiquity all its credit. Finally, Descartes" (an Englishman would have said Bacon), "and some other moderns, have said, 'Phaethon rises because he is drawn up by cords, and because a heavier weight descends.' So now we have come to believe that, if a body move, it is because it is pushed or pulled, and one who could see Nature as it is would simply be seeing what is behind the scenes at the opera."
After this, Fontenelle goes on to sketch the history of his science, and thence to give an account of the Ptolemaic and other systems, which preceded the Copernican. Here, again, a happy image reminds us of a danger all system-makers share, as common partners in a weakness which is as universal as humanity:
"Before I explain the first of these systems, I beg you to remember that—we all of us—are like a certain madman at Athens you may have heard of, who took it into his head that all the ships which came into the harbor belonged to him. Our common failing is to believe all Nature created for our own use, and when you ask our philosophers what end is served by that host of stars, they will calmly tell you, It is there for us to look at.' In this way they could not fail to suppose that the earth was fixed in the centre of the universe, and that all the heavenly bodies were set to revolve about her, and give her light; the same propensity which leads one to desire the most honorable seat at a ceremony makes the philosopher in his system put himself at the centre of the universe if he can."
It will be seen, as Sainte-Beuve remarks, that Fontenelle possesses the art of scientific insinuation in the highest-degree; in addressing his marchioness, he is here appealing to the intelligence of every ignorant person who, rather than resemble the Athenian madman, is cajoled into truth, and disposed in advance to reject Ptolemy's system, in favor of the Copernican.
The account of the Copernican system involves the (to the marchioness) entirely novel idea of the earth's rotation. This is presented to us in a lively picture of the scene which would be offered to a spectator suspended above the surface as the speaker imagines himself to be: "'Passing under my eyes I see all sorts of faces, white, black, and brown. First come hats, and then turbans, and then shaven crowns; now towns with church-spires, now cities with slender, crescent-tipped minarets, now porcelain towers, and then again wide oceans and dreadful deserts.' 'What,' she cries, 'then in the place where we are—I don't mean this park, but this very place in the air—there are people continually passing by, who come where we are now, and at the end of twenty-four hours we get back again ​ourselves!' 'Copernicus,' I replied, 'could not understand it better.'" This novel theme continues to occupy them during their return to the house, and the first evening secures her belief for the new system.
The next morning, on Fontenelle's sending to ask how the lady has passed the night, and to politely inquire whether she has been able to sleep while turning, he is assured that she has already got used to the motion, and was able to rest as soundly as Copernicus himself could have done. With so apt a scholar, progress is rapid, and, by evening, we find them discussing the habitability of the moon, and the cause of the sun's light and heat. What is the view of our author (the subsequent secretary of the Académie des Sciences, and an authority in his day) on the source of supply for this immense expenditure of the solar energy? What theory does he adopt—how was it accounted for in his time? Listen to the explanation of the man who has just satirized so happily the fallacies of the schoolmen. It shines because "it is self-luminous in its nature." And this is given in good faith by Fontenelle as a reason!
Clever as he is, he is here in the bondage of his age; but he might yet have taken a lesson from a contemporary, who, though pretending to no "philosophy," had seen and laughed at the weakness of the learned of his time in thus making words do duty for facts. We remember how the candidate for medical honors in the "Malade Imaginaire," on being asked why opium induces sleep, replies to the delighted satisfaction of the examining Faculty that it is because it possesses a soporific quality! When we see a man so acute as Fontenelle giving a precisely similar answer, with an obtuseness so plain to us, so imperceptible to him, can anything suggest more pertinently the need of watchfulness for traces of this legacy of ancient fallacies of thinking in our own modes of thought?
The third evening is occupied with a further discussion of the moon, and of Venus; on the fourth the other planets are considered, and reasons given for their possible habitability, some of which would hardly satisfy a more modern philosopher. Thus, the ingenious but scarcely satisfactory suggestion is made that, in spite of the neighborhood of Mercury to the sun, that planet may be a comfortable residence, owing to the presence there of large quantities of saltpetre, a substance which (according to our author) gives out "cold exhalations" in the sunshine. Lest this idea be unacceptable to our skeptical age, it should be added that Fontenelle takes care to fortify his position by citing the case of China, large portions of which, it appears, in spite of a southern latitude, experience extreme cold, even to the freezing up of their rivers in July, on account of the existence of this ingredient in their soil!
The "vortices" of Descartes are here introduced and offered as an explanation of the motions of the Jovian satellites about their primaries, and of the principal planets about the sun; and, in the next ​evening, are applied to elucidate the constitution of the milky-way, in which worlds are, it seems, so thick that the plausible suggestion is made that their birds may fly from one to the other!
The remainder of the work is chiefly occupied with a description of the heavenly bodies considered with reference to their possible habitants, and here Fontenelle is not likely to be found tripping, for as to the nature, ways, and modes of living, of the inhabitants of the other planets, he is quite as well informed as we are. We shall find here nearly all that can be said, in the simple absence of any knowledge whatever on the point in question, but we may be more reasonably interested in the happiness of some conjectures offered, where he incidentally speaks of the physical constitution of the bodies he is considering. He tells us, for instance, that the rings of Saturn are supposed to be composed of numberless little moons, close together, and moving in the same orbit; an explanation which appears to have been lost sight of till modern analysis showed that they could not be continuous solids, and modern observation that they could hardly be liquid or gaseous. We have passed over too readily, perhaps, the purely speculative portion of the work, which, if not very instructive, is certainly entertaining, and filled with felicitous illustrations, such as that (too long for quotation) of the citizen of Paris, who maintains that St.-Denis, whose houses he can just distinguish from the towers of Notre-Dame, is uninhabited, because he can see no inhabitants. Or, for still another instance of this art of "scientific insinuation" already referred to, take the passage where the marchioness, after declaring herself dissatisfied with extravagant speculations about the inhabitants of the planets, is told that something positive is, after all, really known about a race on one of them, and which appears from his description to be remarkable indeed. He gives a minute, and, as he asserts, a trustworthy, account of these extraordinary beings, who he would have us believe are most laborious and skillful, yet live by pillage; who have no sex, yet increase as a nation; who subsist in the happiest concord, yet periodically put to death a portion of their innocent fellow-citizens; and so on, until the lady, who finds the story more incredible than any of the preceding speculations, on learning what the race is, and on what planet they exist, is forced to admit that truth may be stranger than fiction, and that no extravagance of his fancies about the possible commonwealths of other worlds surpasses what she has just been entrapped into listening to about that of the bees on our own.
Fontenelle, with all his abundant ingenuity, has one radical defect as a literary artist, and perhaps some will be disposed to add, as a student of Nature. He appears to have no power of moving or being moved by anything like emotion, or of perceiving anything not comprehensible to an intellect divorced from sympathetic intuition. The gallantry which he introduces as an element in the dialogue, and ​which our citations do not undertake to illustrate, is filled, for instance, with ingenious conceits which, though falling coldly on modern ears, were considered in the happiest taste by the audience to whom the book was addressed. But they are of an artificial cleverness, and precisely what we might expect from the man who was said to have "as good a heart as could be made of brains."
Sainte-Beuve has well indicated our author's strength and weakness by comparing his clever opera-box view of Nature with that of Pascal in the majestic movement of the awe-inspired passage at the begining of the "Pensées." While agreeing to the judgment of the great critic, it may be observed, however, that, if Fontenelle be devoid of poetry, he has at least one image of a grace nearly allied to it. He has been speaking of the chances of the sun's light failing us wholly, as it is said to have partially done in the year following the death of Cæsar, and pointing out, with what seems justice, the imperfect grounds for the confidence of mankind in the constancy of Nature's action here in the future as in the past, founded as that confidence is on an experience of the human race—so long, judged by its life, so short in comparison with Nature's own. With a sort of pathetic sense of the fallacy, he compares this little accumulated experience of the generations of man to the traditions of some roses of a day, leaving each to its successor an account of the gardener in whom successive ages of these ephemeral flowers have seen no change. "We have always seen the same gardener; in the memory of roses none has been seen but him; what he has ever been, that he is now: surely he does not die as we, or change."
Fontenelle, throughout the "Conversations," adopts the Cartesian hypothesis of "vortices" in accounting for the planetary movements, and this, indeed, he continued to cling to long after. The true theory of gravitation had been given by Newton, and obtained complete acceptance in England. His more serious work is to be found chiefly in the well-known "Éloges," which, as perpetual secretary of the French Academy of Sciences, he pronounced on its deceased associates; but it is probable that he will, nevertheless, be remembered as much by these "Conversations," which, had they no other merit, would always possess an historical interest, as opening the way to our present popular scientific literature.
We should not close this imperfect notice of them without again reminding the reader that the form of a dialogue gives the original an attraction which is necessarily missed in brief extracts, and that the plan on which they thus rest for uniting instruction and amusement (a plan which obliges the imaginary speaker to be paying his court and talking science at the same time) would have been a failure in almost any hands but those which could manage so difficult a blending, and keep as far from pedantry as from ridicule. Fontenelle's ​gallantry, like his science, may be now a little out of date, but he manages at least to unite these two most opposite conversational ingredients in chemical union. When the lady would send him back from love-making to astronomy, he contrives to give both together, and, consistent to the close, takes leave of his charming scholar with the modest request that, as sole reward for his pains in teaching her the heavens, she will never again look on sun, moon, or stars, without thinking of him.