rnate motion of the {153} two legs,
and creeping, ordinarily precede walking and lead up to it.

What is the natural stimulus to locomotion? It is as difficult to say
as it is to specify the stimulus in other forms of playful activity.
From the fact that blind children are usually delayed in beginning to
walk, we judge that the sense of sight furnishes some of the most
effective stimuli to this response. Often the impulse attending
locomotion is the impulse to approach some seen object, but probably
some satisfaction is derived simply from the free movement itself.
There certainly is no special emotion going with locomotion.
Locomotion has, of course, plenty of "survival value", and might have
been included among the organic instincts.

Some of the other varieties of human locomotion, such as running and
jumping, are probably native. Others, like hopping and skipping, are
probably learned. As to climbing, there is some evolutionary reason
for suspecting that an instinctive tendency in this direction might
persist in the human species, and certainly children show a great
propensity for it; while the acrobatic ability displayed by those
adults whose business leads them to continue climbing is so great as
to raise the question whether the ordinary citizen is right when he
thinks of man as essentially a land-living or surface-living animal.
As to swimming, the theory is sometimes advanced that this too is a
natural form of locomotion for man, and that, consequently, any one
thrown into deep water will swim by instinct. Experiments of this sort
result badly, the victim clutching frantically at any support, and
sometimes dragging down with him the theorist who is administering
this drastic sort of education. In short, the instinctive response of
a man to being in deep water is the same as in other cases of sudden
withdrawal of solid support; it consists in clinging and is attended
by the emotion of fear.

{154}

Vocalization.

Crying at birth proves voice-production to be a native response, but
we are more interested just here in the playful cooing and babbling
that appear when the child is a few weeks or months old. This cheerful
vocalization is also instinctive, in all probability, since the baby
makes it before he shows any signs of responding imitatively to the
voices of other people. It seems to be one form of the random activity
that goes with euphoria. The child derives satisfaction not so much
from the muscular