_Simile of the Watch replaced by Simile of the Flower._
It was in its own chosen stronghold that this once famous argument
was destined to meet its doom. It was in the adaptations of the
organic world, in the manifold harmonies between living creatures
and surrounding circumstances, that it had seemed to find its chief
support; and now came the Darwinian theory of natural selection, and
in the twinkling of an eye knocked all this support from under it.
It is not that the organism and its environment have been adapted to
each other by an exercise of creative intelligence, but it is that
the organism is necessarily fitted to the environment because in the
perennial slaughter that has gone on from the beginning only the
fittest have survived. Or, as it has been otherwise expressed, "the
earth is suited to its inhabitants because it has produced them, and
only such as suit it live." In the struggle for existence no individual
peculiarity, however slight, that tends to the preservation of life
is neglected. It is unerringly seized upon and propagated by natural
selection, and from the cumulative action of such slight causes have
come the beautiful adaptations of which the organic world is full. The
demonstration of this point, through the labours of a whole generation
of naturalists, has been one of the most notable achievements of modern
science, and to the theistic arguments of Paley and the Bridgewater
treatises it has dealt destruction.
But the Darwinian theory of natural selection does not stand alone. It
is part of a greater whole. It is the most conspicuous portion of that
doctrine of evolution in which all the results hitherto attained by
the great modern scientific movement are codified, and which Herbert
Spencer had already begun to set forth in its main outlines before
the Darwinian theory had been made known to the world. This doctrine
of evolution so far extends the range of our vision through past and
future time as entirely to alter our conception of the universe. Our
grandfathers, in common with all preceding generations of men, could
and did suppose that at some particular moment in the past eternity
the world was created in very much the shape which it has at present.
But our modern knowledge does not allow us to suppose anything of the
sort. We can carry back our thoughts through a long succession of
great epochs, some of them many millions of years in duration, in each
of which the innumerable forms of life that covered the earth were
very different from what they were in all the others, and in even the
nearest of which they were notably different from what they are now.
We can go back still farther to the eras when the earth was a whirling
ball of vapour, or when it formed an equatorial belt upon a sun two
hundred million miles in diameter, or when the sun itself was but a
giant nebula from which as yet no planet had been born. And through all
the vast sweep of time, from the simple primeval vapour down to the
multifarious world we know to-day, we see the various forms of Nature
coming into existence one after the other in accordance with laws
of which we are already beginning to trace the character and scope.
Paley's simile of the watch is no longer applicable to such a world as
this. It must be replaced by the simile of the flower. The universe is
not a machine, but an organism, with an indwelling principle of life.
It was not made, but it has grown.
That such a change in our conception of the universe marks the greatest
revolution that has ever taken place in human thinking need scarcely
be said. But even in this statement we have not quite revealed the
depth of the change. Not only has modern science made it clear that the
varied forms of Nature which make up the universe have arisen through a
process of evolution, but it has also made it clear that what we call
the laws of Nature have been evolved through the self-same process.
The axiom of the persistence of force, upon which all modern science
has come to rest, involves as a necessary corollary the persistence of
the relations between forces; so that, starting with the persistence
of force and the primary qualities of matter, it can be shown that all
those uniformities of coexistence and succession which we call natural
laws have arisen one after the other in connection with the forms which
have afforded the occasions for their manifestation. The all-pervading
harmony of Nature is thus itself a natural product, and the last inch
of ground is cut away from under the theologians who suppose the
universe to have come into existence through a supernatural process of
manufacture at the hands of a Creator outside of itself.