ossesses, because as a type of
structure it is as fixed as the species itself, and is indeed a mark
of species. It is not apparent either that we are greatly in need of
another faculty, or that we could make use of it even if by a chance
mutation it should emerge, since with the power of abstraction we are
able to do any class of work we know anything about. Moreover, the
brain is less likely to make a leap now than in earlier time, both
because the conditions of nature are more fixed or more nearly
controlled by man, and hence the urgency of adjustment to sharp
variations in external conditions is removed, and because the struggle
for existence has been mitigated so that the unfit survive along with
the fit. Indeed, the rapid increase in idiocy and insanity shown by
statistics indicates that the brain is deteriorating slightly, _on the
average_, as compared with earlier times.[269]

Nature is not producing a better average brain than in the time of
Aristotle and the Greeks. If we have more than the wisdom of our
ancestors, our advantage lies in our specialization, our superior body
of knowledge, and our superior technique for its transmission. At the
same time, the individual brain is unstable, fluctuating in normal
persons between 1,100 and 1,500 grams in weight, while the extremes
of variation are represented, on the one side, by the imbecile with
300 grams, and the man of genius with 2,000 on the other. It is
therefore perfectly true that by artificial selection--Mr. Galton's
"eugenism"--a larger average brain could be created, and also a higher
average of natural intelligence, whether this be absolutely dependent
on brain weight or not. But it is hardly to be expected that a stable
brain above the capacity of those of the first rank now and in the
past will result, since the mutations of nature are more radical than
the breeding process of man, and she probably ran the whole gamut.
"Great men lived before Agamemnon," and individual variations will
continue to occur, but not on a different pattern; and what has been
true in the past will happen again in the future, that the group which
by hook or by crook comes into possession of the best technique and
the best copies will make the best show of intelligence and march at
the head of civilization.

III

The foregoing examination of the relation of the mental faculty of the
lower races to the higher places us in a position to examine to better
advantage the other