present. Hence--pardon the reiteration--if we can once trace this
sequence of dominant functions, whose evolution has filled past
ages, we can safely foretell something at least of man's future
development.

The argument and method is therefore purely historical. Here and
there we will try to find why and how things had to be so. But all
such digressions are of small account compared with the fact that
things were or are thus and so. And a mistaken explanation will not
invalidate the facts of history.

The subject of our history is the development, not of a single human
race nor of the movements of a century, but the development of
animal life through ages. And even if our attempts to decipher a few
pages here and there in the volumes of this vast biological history
are not as successful as we could hope, we must not allow ourselves
to be discouraged from future efforts. Even if our translation is
here and there at fault, we must never forget the existence of the
history. Some of the worst errors of biologists are due to their
having forgotten that in the lower stages the germs of the higher
must be present, even though invisible to any microscope. Our study
of the worm is inadequate and likely to mislead us, unless we
remember that a worm was the ancestor of man. And a biologist who
can tell us nothing about man is neglecting his fairest field.

Conversely history and social science will rest on a firmer basis
when their students recognize that many human laws and institutions
are heirlooms, the attainments, or direct results of attainments, of
animals far below man. We are just beginning to recognize that the
study of zoölogy is an essential prerequisite to, and firm