y then had living significance in the mouths
of those who used them, though they have become such mere shibboleths
and cant formulae to ourselves that we think no more of their meaning
than we do of Julius Caesar in the month of July. They continue to be
reproduced through the force of habit, and through indisposition to get
out of any familiar groove of action until it becomes too unpleasant for
us to remain in it any longer. It has long been felt that embryology and
rudimentary structures indicated community of descent. Dr. Darwin and
Lamarck insisted on this, as have all subsequent writers on evolution;
but the explanation of why and how the structures come to be
repeated--namely, that they are simply examples of the force of
habit--can only be perceived intelligently by those who admit so much
unity between parents and offspring that the self-development of the
latter can be properly called habitual (as being a repetition of an act
by one and the same individual), and can only be fully sympathized with
by those who recognize that if habit be admitted as the key to the fact
at all, the unconscious manner in which the habit comes to be repeated
is only of a piece with all our other observations concerning habit. For
the fuller development of the foregoing, I must refer the reader to my
work 'Life and Habit.'

The purposiveness, which even Dr. Darwin, and Lamarck still less, seem
never to have quite recognized in spite of their having insisted so much
on what amounts to the same thing, now comes into full view. It is seen
that the organs external to the body, and those internal to it are, the
second as much as the first, things which we have made for our own
convenience, and with a prevision that we shall have need of them; the
main difference between the manufacture of these two classes of organs
being, that we have made the one kind so often that we can no longer
follow the processes whereby we make them, while the others are new
things which we must make introspectively or not at all, and which are
not yet so incorporate with our vitality as that we should think they
grow instead of being manufactured. The manufacture of the tool, and the
manufacture of the living organ prove therefore to be but two species of
the same genus, which, though widely differentiated, have descended as
it were from one common filament of desire and inventive faculty. The
greater or less complexity of the organs goes for very little. It is