rigin of
Species is given in the account of his books, written by himself and
already referred to. His letter to Professor Asa Gray (September 5th,
1857) is a most valuable brief exposition of his theory and an admirable
sample of his correspondence. The distinguished American botanist was
one of his most constant correspondents and a dear personal friend.

I have also given as an extract the final pages of the 'Origin of
Species,' in which Darwin eloquently defends the view of nature to which
his theory leads. A similar and important passage on the subject of
'Creative Design' is also given: it is taken from that wonderful
collection of facts and arguments published by Darwin under the title of
'The Variation of Plants and Animals under Domestication.' It cannot be
too definitely stated, as Darwin himself insisted, that his theory of
the Origin of Species is essentially an extension of the argument used
by Lyell in his 'Principles of Geology.' Just as Lyell accounted for the
huge masses of stratified rocks, the upheaved mountain chains, the deep
valleys, and the shifting seas of the earth's surface, by adducing the
long-continued cumulative action of causes which are at this present
moment in operation and can be observed and measured at the present day:
so Darwin demonstrates that natural variation, and consequent selection
by "breeders" and "fanciers" at the present day, give rise to new forms
of plants and animals; and that the cumulative, long-continued action of
_Natural_ Selection in the Struggle for Existence, or the survival of
favorable variations, can and must have effected changes, the magnitude
of which is only limited by the length of time during which the process
has been going on.

The style of Darwin's writings is remarkable for the absence of all
affectation, of all attempt at epigram, literary allusion, or rhetoric.
In this it is admirably suited to its subject. At the same time there is
no sacrifice of clearness to brevity, nor are technical terms used in
place of ordinary language. The greatest pains are obviously given by
the author to enable his reader to thoroughly understand the matter in
hand. Further, the reader is treated not only with this courtesy of full
explanation, but with extreme fairness and modesty. Darwin never slurs
over a difficulty nor minimizes it. He states objections and awkward
facts prominently, and without shirking proceeds to deal with them by
citation of experiment or ob