focation by wind in early
infancy, is now winning at least the provisional assent of all the best
thinkers of the day--the hypothesis that the forms or species of living
beings, as we know them, have been produced by the gradual modification
of pre-existing species--then the existence of persistent types seems
to teach us much. Just as a small portion of a great curve appears
straight, the apparent absence of change in direction of the line being
the exponent of the vast extent of the whole, in proportion to the part
we see; so, if it be true that all living species are the result of the
modification of other and simpler forms, the existence of these little
altered persistent types, ranging through all geological time, must
indicate that they are but the final terms of an enormous series of
modifications, which had their being in the great lapse of pregeologic
time, and are now perhaps for ever lost.

In other words, when rightly studied, the teachings of palaeontology are
at one with those of physical geology. Our farthest explorations carry
us back but a little way above the mouth of the great river of Life:
where it arose, and by what channels the noble tide has reached the
point when it first breaks upon our view, is hidden from us.

The foregoing pages contain the substance of a lecture delivered before
the Royal Institution of Great Britain many months ago, and of course
long before the appearance of the remarkable work on the "Origin of
Species" just published by Mr. Darwin, who arrives at very similar
conclusions. Although, in one sense, I might fairly say that my own
views have been arrived at independently, I do not know that I can
claim any equitable right to property in them; for it has long been
my privilege to enjoy Mr. Darwin's friendship, and to profit by
corresponding with him, and by, to some extent, becoming acquainted with
the workings of his singularly original and well-stored mind. It was in
consequence of my knowledge of the general tenor of the researches
in which Mr. Darwin had been so long engaged; because I had the most
complete confidence in his perseverance, his knowledge, and, above all
things, his high-minded love of truth; and, moreover, because I found
that the better I became acquainted with the opinions of the best
naturalists regarding the vexed question of species, the less fixed
they seemed to be, and the more inclined they were to the hypothesis
of gradual modification, that I ven