uading not a few people of the validity of the idea of evolution.
He probably could have convinced many more had it not been for the
hostility of Cuvier. Accordingly, Charles Darwin's "Origin of
Species" fell upon a world entirely hostile to the idea, when it
thought of it at all. Within fifty years of the publication of this
wonderful book, probably the entire scientific world is agreed that
evolution, in some form or other, is the undoubted solution of the
mystery of creation. The materialist may think of it as a mechanical
process relentlessly working itself out without design or purpose. The
theist will accept it as the plan by which Eternal Power steadily
works. The devout Christian or Jew will see in it God's method of
creation. The idea of development has penetrated every science that
has to do with animals or man. It is even beginning to influence such
inorganic sciences as Physics and Chemistry. We now hear of the
evolution of the elements, and the evolution of forces. The world has
been persuaded that evolution is true, and this is primarily the
result of the work of Charles Darwin. It is astonishing that so great
a revolution should have come in so short a time.

The other phase of Darwin's work was his attempt to find the agent
which is bringing about the actual transformation of animals and
plants. As we have seen in the preceding chapters, it was his idea
that natural selection was the efficient agent which constantly
eliminated all unfit variations, leaving only the best to carry on the
work of the world and to reproduce their own fit kind. Many
biologists since his time have doubted whether unaided Natural
Selection will account for the constant advance in organisms. This is
the part of the work which is often seriously questioned.

Weissman and his co-workers have contended that this unaided principle
will serve. Most biologists have asked for some more efficient cause,
and assert that selection does not account for the appearance of
variations, but only for their preservation, and that any valid theory
of evolution must show how variations originate. It is chiefly in this
respect that Darwin's work has failed to satisfy many later
biologists. When we hear a scientist speak of Darwinism as being dead,
this is what he means. He does not think evolution false, but believes
that Natural Selection is not sufficient to account for evolution.
There are three main difficulties involved in Darwin's theory. The