cond inquiry.

When, indeed, the history comes to be written of that great revolution
of thought in the nineteenth century, by which the doctrine of
evolution, from being the dream of poets and visionaries, gradually grew
to be the accepted creed of naturalists, the paramount influence exerted
by the infant science of geology--and especially that resulting from
the publication of Lyell's epoch-making work, the "Principles of
Geology"--cannot fail to be regarded as one of the leading factors.
Herbert Spencer in his "Autobiography" bears testimony to the effect
produced on his mind by the recently published "Principles", when, at
the age of twenty, he had already begun to speculate on the subject
of evolution (Herbert Spencer's "Autobiography", London, 1904, Vol. I.
pages 175-177.); and Alfred Russel Wallace is scarcely less emphatic
concerning the part played by Lyell's teaching in his scientific
education. (See "My Life; a record of Events and Opinions", London,
1905, Vol. I. page 355, etc. Also his review of Lyell's "Principles"
in "Quarterly Review" (Vol. 126), 1869, pages 359-394. See also "The
Darwin-Wallace Celebration by the Linnean Society" (1909), page 118.)
Huxley wrote in 1887 "I owe more than I can tell to the careful study
of the "Principles of Geology" in my young days." ("Science and Pseudo
Science"; "Collected Essays", London, 1902, Vol. V. page 101.) As for
Charles Darwin, he never tired--either in his published writings, his
private correspondence or his most intimate conversations--of ascribing
the awakening of his enthusiasm and the direction of his energies
towards the elucidation of the problem of development to the "Principles
of Geology" and the personal influence of its author. Huxley has well
expressed what the author of the "Origin of Species" so constantly
insisted upon, in the statements "Darwin's greatest work is the outcome
of the unflinching application to Biology of the leading idea and the
method applied in the "Principles" to Geology ("Proc. Roy. Soc." Vol.
XLIV. (1888), page viii.; "Collected Essays" II. page 268, 1902.), and
"Lyell, for others, as for myself, was the chief agent in smoothing the
road for Darwin." ("Life and Letters of Charles Darwin" II. page 190.)

We propose therefore to consider, first, what Darwin owed to geology and
its cultivators, and in the second place how he was able in the end so
fully to pay a great debt which he never failed to acknowledge. Thanks
to the