k. As
one result of this, he does not learn from individual experience,
but one generation is like the preceding generations, with here and
there some slight modifications. But when you get the creature
that has arrived at the point where his experience has become
varied, he has got to do a good many things, and there is more or
less individuality about them; and many of them are not performed
with the same minuteness and regularity, so that there does not
begin to be that automatism within the period during which he is
being developed and his form is taking on its outlines. During
prenatal life there is not time enough for all these nervous
registrations, and so by degrees it comes about that he is born
with his nervous system perfectly capable only of making him
breathe and digest food,--of making him do the things absolutely
requisite for supporting life; instead of being born with a certain
number of definite developed capacities, he has a number of
potentialities which have got to be roused according to his own
individual experience. Pursuing that line of thought, it began
after a while to seem clear to me that the infancy of the animal in
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 r