of their own passions
and their clear adjustment to one another. That complete
agreement between man's desires and the environment in
which alone they can find their satisfaction remains at
best an ideal. But it is an ideal which indicates clearly the function
of control. This is obviously not to crush native desires, but
to organize their harmonious fulfillment. Where men have
an opportunity to utilize their native gifts they will be satisfied
and interested; where native capacities and desires are
continually balked, men will be discontented though
well-regimented machines.

HABITUAL BEHAVIOR. Except for purposes of analysis, life on
the purely instinctive level may be said scarcely to exist in
contemporary society, or for that matter, since the beginnings
of recorded history. As has been already pointed out,
while men are born with an even wider variety of tendencies
to act than animals, these are much more plastic and modifiable,
more susceptible of training, and much more in need of it
than those of the sub-human forms. Even among animals
under conditions of domestication, instinct tends largely to be
replaced by habitual or acquired modes of behavior. The
human being, born with a nervous system and a brain in extremely
unformed and plastic condition, is so susceptible to
every influence current in his environment that most of his
actions within a few years after birth are, when they are not
the result of deliberate reflection, secondary or habitual rather
than genuinely instinctive. That is, few of the simplest actions
of human beings are not in some degree modified by experience.
They may appear just as automatic and immediate
as if they were instinctive, and indeed they are, but they are
learned ways rather than the unlearned ways man has as his
possession at birth.

THE MECHANISM OF HABIT. The implications of habitual behavior
can better be understood after a brief analysis of the
mechanism of such action. An instinct has been defined as a
tendency to act in a given way in response to a given stimulus.
What happens when a stimulus prompts the organism
to respond in a given way, is that some sensory nerve, whether
of taste or touch or sound, sight, smell, or muscular sensitivity,
receives a stimulus which passes through the spinal cord
to a motor nerve through which some muscle is "innervated"
and a response made. In the simplest type of reflex action,
such as the winking of an eye in a blinding light, o