uried in the Abbey.

In all the glorious company of immortal dead whose earthly frames are
gathered in England's great mausoleum, there is no other one who has
done so much to modify the mind of thinking man.

CHAPTER III

THE UNDERLYING IDEA

We have seen in the preceding chapters how the idea of evolution
worked its way through the minds of men. Man after man got a glimpse
of the idea, even among the ancient philosophers. But no one could
speak convincingly on the subject before modern times, when a wider
acquaintance with the animal world gave a body of facts on which it
was safe to base conclusions. Even then the idea eluded men, until
there came a worker trained by a long voyage around the world in which
he had nothing to do except to study nature. He finally gathered in
his mind material sufficient to convince himself not only of the truth
of evolution but of the process by which this evolution was brought
about. Every scientific principle is simple in its basal idea. In
actual life the action of the principle may be so bound up with others
as to need a skillful mind for its detection. But under all the
complexities and modifications, like a silver thread woven into a
cloth, runs the basal idea. Until a master has detected it the
presence of it may be unsuspected. But once discovered and expounded,
thereafter anyone may follow out its workings. So it is with the
Darwinian idea of selection. It waited long for a discoverer, but,
once found, we cannot but wonder why men did not see it earlier, it is
so simple.

Mr. Darwin's mind, while slow and cautious, had a wonderful
perseverance. When he had finished his work he had not only given a
clear account of the process of evolution, but he had foreseen almost
all the valid objections that were afterward to be brought against his
theory. Some of them he had explained quite fully; of others he
indicated a possible explanation; of still other questions he
confessed that as yet they were not plain. But the whole theory is so
simple in its fundamental ideas that it has completely revolutionized
the whole aspect of modern biology and, indeed, of modern thinking in
many lines.

There are four underlying conceptions, each simple in itself, which
must be clearly perceived before one can understand Mr. Darwin's
theory of "Natural Selection." The first of these is known under the
name of Heredity. It is a matter of common observation that every
animal or plant pro