Darwin metaphor

Category:TauTology
Darwin's usage of metaphor in OoS
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THE TERM, STRUGGLE FOR EXISTENCE, USED IN A LARGE SENSE.
I should premise that I use this term in a large and metaphorical sense,
including dependence of one being on another, and including (which is more
important) not only the life of the individual, but success in leaving
progeny. Two canine animals, in a time of dearth, may be truly said to
struggle with each other which shall get food and live. But a plant on the
edge of a desert is said to struggle for life against the drought, though
more properly it should be said to be dependent on the moisture. A plant
which annually produces a thousand seeds, of which only one of an average
comes to maturity, may be more truly said to struggle with the plants of
the same and other kinds which already clothe the ground. The mistletoe is
dependent on the apple and a few other trees, but can only in a far-fetched
sense be said to struggle with these trees, for, if too many of these
parasites grow on the same tree, it languishes and dies. But several
seedling mistletoes, growing close together on the same branch, may more
truly be said to struggle with each other. As the mistletoe is
disseminated by birds, its existence depends on them; and it may
metaphorically be said to struggle with other fruit-bearing plants, in
tempting the birds to devour and thus disseminate its seeds. In these
several senses, which pass into each other, I use for convenience sake the
general term of Struggle for Existence.
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Several writers have misapprehended or objected to the term Natural
Selection. Some have even imagined that natural selection induces
variability, whereas it implies only the preservation of such variations as
arise and are beneficial to the being under its conditions of life. 
No one objects to agriculturists speaking of the potent effects of man's
selection; and in this case the individual differences given by nature,
which man for some object selects, must of necessity first occur. 
Others have objected that the term selection implies conscious choice in the
animals which become modified; and it has even been urged that, as plants
have no volition, natural selection is not applicable to them! 
In the literal sense of the word, no doubt, natural selection is a false term; but
who ever objected to chemists speaking of the elective affinities of the
various elements?--and yet an acid cannot strictly be said to elect the
base with which it in preference combines.
It has been said that I speak of natural selection as an active power or Deity; but who objects to an
author speaking of the attraction of gravity as ruling the movements of the
planets? Every one knows what is meant and is implied by such metaphorical
expressions; and they are almost necessary for brevity. So again it is
difficult to avoid personifying the word Nature; but I mean by nature, only
the aggregate action and product of many natural laws, and by laws the
sequence of events as ascertained by us. With a little familiarity such
superficial objections will be forgotten.
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 He often begins his selection by some half-monstrous form, or
at least by some modification prominent enough to catch the eye or to be
plainly useful to him. Under nature, the slightest differences of
structure or constitution may well turn the nicely-balanced scale in the
struggle for life, and so be preserved. How fleeting are the wishes and
efforts of man! How short his time, and consequently how poor will be his
results, compared with those accumulated by Nature during whole geological
periods! Can we wonder, then, that Nature's productions should be far
"truer" in character than man's productions; that they should be infinitely
better adapted to the most complex conditions of life, and should plainly
bear the stamp of far higher workmanship?
It may metaphorically be said that natural selection is daily and hourly
scrutinising, throughout the world, the slightest variations; rejecting
those that are bad, preserving and adding up all that are good; silently
and insensibly working, WHENEVER AND WHEREVER OPPORTUNITY OFFERS, at the
improvement of each organic being in relation to its organic and inorganic
conditions of life. We see nothing of these slow changes in progress,
until the hand of time has marked the long lapse of ages, and then so
imperfect is our view into long-past geological ages that we see only that
the forms of life are now different from what they formerly were.
In order that any great amount of modification should be effected in a
species, a variety, when once formed must again, perhaps after a long
interval of time, vary or present individual differences of the same
favourable nature as before; and these must again be preserved, and so
onward, step by step. Seeing that individual differences of the same kind
perpetually recur, this can hardly be considered as an unwarrantable
assumption. But whether it is true, we can judge only by seeing how far
the hypothesis accords with and explains the general phenomena of nature.
On the other hand, the ordinary belief that the amount of possible
variation is a strictly limited quantity, is likewise a simple assumption.
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The several difficulties here discussed, namely, that, though we find in
our geological formations many links between the species which now exist
and which formerly existed, we do not find infinitely numerous fine
transitional forms closely joining them all together. The sudden manner in
which several groups of species first appear in our European formations,
the almost entire absence, as at present known, of formations rich in
fossils beneath the Cambrian strata, are all undoubtedly of the most
serious nature. We see this in the fact that the most eminent
palaeontologists, namely, Cuvier, Agassiz, Barrande, Pictet, Falconer, E.
Forbes, etc., and all our greatest geologists, as Lyell, Murchison,
Sedgwick, etc., have unanimously, often vehemently, maintained the
immutability of species. But Sir Charles Lyell now gives the support of
his high authority to the opposite side, and most geologists and
palaeontologists are much shaken in their former belief. Those who believe
that the geological record is in any degree perfect, will undoubtedly at
once reject my theory. For my part, following out Lyell's metaphor, I look
at the geological record as a history of the world imperfectly kept and
written in a changing dialect. Of this history we possess the last volume
alone, relating only to two or three countries. Of this volume, only here
and there a short chapter has been preserved, and of each page, only here
and there a few lines. Each word of the slowly-changing language, more or
less different in the successive chapters, may represent the forms of life,
which are entombed in our consecutive formations, and which falsely appear
to have been abruptly introduced. On this view the difficulties above
discussed are greatly diminished or even disappear.
But I must explain my meaning more fully. I believe that the ARRANGEMENT
of the groups within each class, in due subordination and relation to each
other, must be strictly genealogical in order to be natural; but that the
AMOUNT of difference in the several branches or groups, though allied in
the same degree in blood to their common progenitor, may differ greatly,
being due to the different degrees of modification which they have
undergone; and this is expressed by the forms being ranked under different
genera, families, sections or orders. The reader will best understand what
is meant, if he will take the trouble to refer to the diagram in the fourth
chapter. We will suppose the letters A to L to represent allied genera
existing during the Silurian epoch, and descended from some still earlier
form. In three of these genera (A, F, and I) a species has transmitted
modified descendants to the present day, represented by the fifteen genera
(a14 to z14) on the uppermost horizontal line. Now, all these modified
descendants from a single species are related in blood or descent in the
same degree. They may metaphorically be called cousins to the same
millionth degree, yet they differ widely and in different degrees from each
other. The forms descended from A, now broken up into two or three
families, constitute a distinct order from those descended from I, also
broken up into two families. Nor can the existing species descended from A
be ranked in the same genus with the parent A, or those from I with parent
I. But the existing genus F14 may be supposed to have been but slightly
modified, and it will then rank with the parent genus F; just as some few
still living organisms belong to Silurian genera. So that the comparative
value of the differences between these organic beings, which are all
related to each other in the same degree in blood, has come to be widely
different. Nevertheless, their genealogical ARRANGEMENT remains strictly
true, not only at the present time, but at each successive period of
descent. All the modified descendants from A will have inherited something
in common from their common parent, as will all the descendants from I; so
will it be with each subordinate branch of descendants at each successive
stage. If, however, we suppose any descendant of A or of I to have become
so much modified as to have lost all traces of its parentage in this case,
its place in the natural system will be lost, as seems to have occurred
with some few existing organisms. 
Messrs. Wallace and Trimen have likewise described several equally striking
cases of imitation in the Lepidoptera of the Malay Archipelago and Africa,
and with some other insects. Mr. Wallace has also detected one such case
with birds, but we have none with the larger quadrupeds. The much greater
frequency of imitation with insects than with other animals, is probably
the consequence of their small size; insects cannot defend themselves,
excepting indeed the kinds furnished with a sting, and I have never heard
of an instance of such kinds mocking other insects, though they are mocked;
insects cannot easily escape by flight from the larger animals which prey
on them; therefore, speaking metaphorically, they are reduced, like most
weak creatures, to trickery and dissimulation.
Most naturalists, however, use such language only in a metaphorical sense: 
they are far from meaning that during a long course of descent, primordial
organs of any kind--vertebrae in the one case and legs in the other--have
actually been converted into skulls or jaws. Yet so strong is the
appearance of this having occurred that naturalists can hardly avoid
employing language having this plain signification. According to the views
here maintained, such language may be used literally; and the wonderful
fact of the jaws, for instance, of a crab retaining numerous characters,
which they probably would have retained through inheritance, if they had
really been metamorphosed from true though extremely simple legs, is in
part explained.
The other and more general departments of natural history will rise greatly
in interest. The terms used by naturalists, of affinity, relationship,
community of type, paternity, morphology, adaptive characters, rudimentary
and aborted organs, etc., will cease to be metaphorical and will have a
plain signification. When we no longer look at an organic being as a
savage looks at a ship, as something wholly beyond his comprehension; when
we regard every production of nature as one which has had a long history;
when we contemplate every complex structure and instinct as the summing up
of many contrivances, each useful to the possessor, in the same way as any
great mechanical invention is the summing up of the labour, the experience,
the reason, and even the blunders of numerous workmen; when we thus view
each organic being, how far more interesting--I speak from experience--does
the study of natural history become!