a whole. Nature is,
therefore, always picking out, or selecting, such individuals to live
and to breed.

The third fact is, that the individuals so selected transmit their
favourable qualities to their offspring by heredity. There is no doubt
about this fact, so far as we are concerned with it. For although, as I
have already hinted, considerable doubt has of late years been cast upon
Lamarck's doctrine of the hereditary transmission of _acquired_
characters, it remains as impossible as ever it was to question the
hereditary transmission of what are called _congenital_ characters. And
this is all that Darwin's theory necessarily requires.

The fourth fact is, that although heredity as a whole produces a
wonderfully exact copy of the parent in the child, there is never a
precise reduplication. Of all the millions of human beings upon the face
of the earth, no one is so like another that we cannot see some
difference; the resemblance is everywhere specific, nowhere individual.
Now this same remark applies to all specific types. The only reason why
we notice individual differences in the case of the human type more than
we do in the case of any other types, is because our attention is here
more incessantly focussed upon these differences. We are compelled to
notice them in the case of our own species, however small they may
appear to a naturalist, because, unless we do so, we should not
recognise the members of our own family, or be able to distinguish
between a man whom we know is ready to do us an important service, and
another man whom we know is ready to cut our throats. But our common
mother Nature is able thus to distinguish between all her children. Her
eyes are much more ready to detect small individual peculiarities than
are the eyes of any naturalist. No slight variations in the cast of
feature or disposition of parts, no minute difference in the arrangement
of microscopical cells, can escape her ever vigilant attention. And,
consequently, when among all the innumerable multitudes of individual
variations any one arises which--no matter in how slight a degree--gives
to that individual a better chance of success in the struggle for life,
Nature chooses that individual to survive, and so to perpetuate the
improvement in his or her progeny.

Now I say that all these several component parts of Darwinian doctrine
are not matters of theory, but matters of fact. The only element of
theory in his doctrine of evolution