son was
provided them, they turned to the store of facts within their own
knowledge, and rapidly arranged the evidence which had been lurking
only partly visible in favour of the fact of evolution. It cannot be
disputed that here and there earlier writers than Darwin and Wallace
had suggested the possibility of natural selection acting upon
existing variations so as to cause survival of the fittest.
MacGillivray, the Scots naturalist, and the father of Huxley's
companion on the _Rattlesnake_, had published suggestions which came
exceedingly near to Darwin's theory. In 1831 Mr. Patrick Matthew had
published a work on _Naval Architecture and Timber_, and in it had
stated the essential principle of the Darwinian doctrine of struggle
and survival. Still earlier, in 1813, a Dr. W.C. Wells, in a paper to
the Royal Society on "A White Female, Part of whose Skin Resembles
that of a Negro," had, as Darwin himself freely admitted, distinctly
recognised the principle of natural selection--but applied it only to
the races of man, and to certain characters alone. Finally, long
before either of these, Aristotle himself had written, in _Physics_,
ii., 8: "Why are not the things which seem the result of design,
merely spontaneous variations, which, being useful, have been
preserved, while others are continually eliminated as unsuitable?"
None of these foreshadowings were supported by lengthy evidence, nor
worked out into an elaborate theory; and it was not until Darwin had
done this that we can say the birth of natural selection really took
place. Huxley writes:

"The suggestion that new species may result from the selective
action of external conditions upon the variations from their
specific type which individuals present,--and which we call
'spontaneous,' because we are ignorant of their causation,--is
as wholly unknown to the historian of scientific ideas as it was
to biological specialists before 1858."

But that suggestion is the central idea of the origin of species, and
contains the quintessence of Darwinism.

Some weeks before the _Origin_ was published, Darwin wrote to Huxley,
sending him a copy of the work, and asking him for the names of
eminent foreigners to whom it should be sent. In the course of his
letter he wrote: "I shall be intensely curious to hear what effect the
book produces on you," and it was clear that he had no very confident
expectation of a favourable opinion. Huxley repli