a very undeveloped condition, with the larger part of his faculties
in potentiality rather than in actuality, was a direct result of
the increase of intelligence, and I began to see that now we have
two steps: first, natural selection goes on increasing the
intelligence; and secondly, when the intelligence goes far enough,
it makes a longer infancy, a creature is born less developed, and
therefore there comes this plastic period during which he is more
teachable. The capacity for progress begins to come in, and you
begin to get at one of the great points in which man is
distinguished from the lower animals, for one of those points is
undoubtedly his progressiveness; and I think that any one will say,
with very little hesitation, that if it were not for our period of
infancy we should not be progressive. If we came into the world
with our capacities all cut and dried, one generation would be very
much like another.

Then, looking round to see what are the other points which are most
important in which man differs from the lower animals, there comes
that matter of the family. The family has adumbrations and
foreshadowings among the lower animals, but in general it may be
said that while mammals lower than man are gregarious, in man have
become established those peculiar relationships which constitute
what we know as the family; and it is easy to see how the existence
of helpless infants would bring about just that state of things.
The necessity of caring for the infants would prolong the period of
maternal affection, and would tend to keep the father and mother
and children together, but it would tend especially to keep the
mother and children together. This business of the marital
relations was not really a thing that became adjusted in the
primitive ages of man, but it has become adjusted in the course of