the supply of blood to that part, or of one of the muscles to which it
is distributed, might render all of us dumb. But a race of dumb men,
deprived of all communication with those who could speak, would be
little indeed removed from the brutes. And the moral and intellectual
difference between them and ourselves would be practically infinite,
though the naturalist should not be able to find a single shadow of
even specific structural difference.

But let me dismiss this question now, and, in conclusion, let me say
that you may go away with it as my mature conviction, that Mr. Darwin's
work is the greatest contribution which has been made to biological
science since the publication of the 'Regne Animal' of Cuvier, and
since that of the 'History of Development' of Von Baer. I believe that
if you strip it of its theoretical part it still remains one of the
greatest encyclopaedias of biological doctrine that any one man ever
brought forth; and I believe that, if you take it as the embodiment of
an hypothesis, it is destined to be the guide of biological and
psychological speculation for the next three or four generations.