of 1859, and since none of those who got
hold of the idea made any use of it. What Darwin did was to follow the
clue which Malthus gave him, to realise, first by genius and
afterwards by patience, how the complex and subtle struggle for
existence works out a natural selection of those organisms which vary
in the direction of fitter adaptation to the conditions of their life.
So much success attended his application of the Selection-formula that
for a time he regarded Natural Selection as almost the sole factor in
evolution, variations being pre-supposed; gradually, however, he came
to recognise that there was some validity in the factors which had
been emphasised by Lamarck and by Buffon, and in his well known
summing up in the sixth edition of the _Origin_ he says of the
transformation of species: "This has been effected chiefly through the
natural selection of numerous successive, slight, favourable
variations; aided in an important manner by the inherited effects of
the use and disuse of parts; and in an unimportant manner, that is, in
relation to adaptive structures, whether past or present, by the
direct action of external conditions, and by variations which seem to
us in our ignorance to arise spontaneously."

To sum up: the idea of organic evolution, older than Aristotle, slowly
developed from the stage of suggestion to the stage of verification,
and the first convincing verification was Darwin's; from being an _a
priori_ anticipation it has become an interpretation of nature, and
Darwin is still the chief interpreter; from being a modal
interpretation it has advanced to the rank of a causal theory, the
most convincing part of which men will never cease to call Darwinism.

FOOTNOTES:

[Footnote 1: _Columbia University Biological Series_, Vol. I. New York
and London, 1894. We must acknowledge our great indebtedness to this
fine piece of work.]

[Footnote 2: _op. cit._ p. 41.]

[Footnote 3: See G. J. Romanes, "Aristotle as a Naturalist,"
_Contemporary Review_, Vol. lix. p. 275, 1891; G. Pouchet, _La
Biologie Aristotelique_, Paris, 1885; E. Zeller, _A History of Greek
Philosophy_, London, 1881, and "Ueber die griechischen Vorgaenger
Darwin's," _Abhandl. Berlin Akad._ 1878, pp. 111-124.]

[Footnote 4: _op. cit._ p. 81.]

[Footnote 5: _op. cit._ p. 87.]

[Footnote 6: See Brock, "Die Stellung Kant's zur Deszendenztheorie,"
_Biol. Centralbl._ viii. 1889, pp. 641-648. Fritz Schultze, _Kant und
Darwin_, Jena, 1