The hypothesis of evolution supposes that in all this vast
progression there would be no breach of continuity, no point at
which we could say "This is a natural process," and "This is not
a natural process;" but that the whole might be compared to that
wonderful operation of development which may be seen going on
every day under our eyes, in virtue of which there arises, out
of the semi-fluid comparatively homogeneous substance which we
call an egg, the complicated organisation of one of the higher
animals. That, in a few words, is what is meant by the
hypothesis of evolution or Quicksilver.
