The final word of science, so far, is that we have at least two,
perhaps three, great families of human beings–the whites and
Negroes, possibly the yellow race. That other races have arisen
from the intermingling of the blood of these two. This broad
division of the world's races which men like Huxley and Raetzel
have introduced as more nearly true than the old five-race
scheme of Blumenbach, is nothing more than an acknowledgment
that, so far as purely physical characteristics are concerned,
the differences between men do not explain all the differences
of their history. It declares, as Darwin himself said, that
great as is the physical unlikeness of the various races of men
their likenesses are greater, and upon this rests the whole
scientific doctrine of Human Brotherhood.

Although the wonderful developments of human history teach
that the grosser physical differences of color, hair and bone go
but a short way toward explaining the different roles which
groups of men have played in Human Progress, yet there are
differences–subtle, delicate and elusive, though they may be–
which have silently but definitely separated men into groups.
While these subtle forces have generally followed the natural
cleavage of common blood, descent and physical peculiarities,
they have at other times swept across and ignored these. At all
times, however, they have divided human beings into races,
which, while they perhaps transcend scientific definition,
nevertheless, are clearly defined to the eye of the Historian
and Sociologist.

If this be true, then the history of the world is the
history, not of individuals, but of groups, not of nations, but