The immense number and strength of these random, impulsive movements in the
infant is in great contrast to the few, instinctive, unchangeable modes of
action in lower animals. As already stated, most animals come to the world
with the few movements necessary to their existence already provided for
and so fixed that future adjustment to new conditions is practically
impossible. The child, on the other hand, has marvelous capacity for
adjustment to new conditions and presents, therefore, possibilities for
training and education that have probably never yet been fully realized in
any child.

The reflexes and instincts, however, are much more fixed and certain in
their action than are the impulses. No matter what the training and
education of an individual may be, he will sneeze, even in church, if the
right stimulus is present; or he will cry and shed tears in public if the
melodrama excites the proper nerve centers. When the sex instinct is fully
aroused or the sentiment of love completely awakened, no one can foretell
what the action of the otherwise sane person will be.

All that training and education can do is to inhibit under ordinary
conditions certain undesirable tendencies and instincts and to strengthen
through exercise those that are desirable; and even then when a crisis
comes, the old, hereditary instinct is apt to break through its thin veneer
and actually frighten the individual at the unexpected strength it reveals.
Slap any man in the face and see what chance his life-long education has
against the old barbarous instinct for fighting. But notwithstanding the
strength and tenacity of instincts, training and education may inhibit
some of them and so transform others into useful habits that for most
purposes in life their subjugation seems complete.

A tremendous, almost divine power rests, therefore, in the hands of