of the mutability of species was thus prominently
raised.

Those who rate Lamarck no higher than did Huxley in his contemptuous
phrase "_buccinator tantum_," will scarcely deny that the sound of the
trumpet had carried far, or that its note was clear. If then there
were few who had already turned to evolution with positive conviction,
all scientific men must at least have known that such views had been
promulgated; and many must, as Huxley says, have taken up his own
position of "critical expectancy."[59]

Why, then, was it, that Darwin succeeded where the rest had failed?
The cause of that success was twofold. First, and obviously, in the
principle of Natural Selection he had a suggestion which would work.
It might not go the whole way, but it was true as far as it went.
Evolution could thus in great measure be fairly represented as a
consequence of demonstrable processes. Darwin seldom endangers the
mechanism he devised by putting on it strains much greater than it can
bear. He at least was under no illusion as to the omnipotence of
Selection; and he introduces none of the forced pleading which in
recent years has threatened to discredit that principle.

For example, in the latest text of the _Origin_[60] we find him
saying:

"But as my conclusions have lately been much misrepresented,
and it has been stated that I attribute the modification of
species exclusively to natural selection, I may be permitted
to remark that in the first edition of this work, and
subsequently, I placed in a most conspicuous
position--namely, at the close of the Introduction--the
following words: 'I am convinced that natural selection has
been the main but not the exclusive means of modification.'"

But apart from the invention of this reasonable hypothesis, which may
well, as Huxley estimated, "be the guide of biological and
psychological speculation for the next three or four generations,"
Darwin made a more significant and imperishable contribution. Not for
a few generations, but through all ages he should be remembered as the
first who showed clearly that the problems of Heredity and Variation
are soluble by observation, and laid down the course by which we must
proceed to their solution.[61] The moment of inspiration did not come
with the reading of Malthus, but with the opening of the "first
note-book on Transmutation of Species."[62] Evolution is a process of
Variation and Heredity.