had made in the
utilization of the natural resources about him. We date the
remote periods of mankind chiefly by the mementos we have
of the kinds of tools they used and the methods they had
developed in the control of their environment. The knowledge
of how to start and maintain a fire has been set down
as the practical beginning of civilization. Certainly next in
importance was the invention of the simplest tools. There
came in succession, though aeons apart, the use of chipped
stone implements, bronze or copper instruments, and instruments
made of iron. In the ancient world we find the invention
of such simple machines as the pulley, the use of rope,
and the inclined plane.

Without tracing the history of invention, it will suffice for
our purpose to point out that agriculture and industry, men's
modes of exploiting Nature, are dependent intimately on the
effectiveness of the tools at their disposal. It is a far cry
from the flint hatchet to the McCormick reaper and the modern
steel works, but these are two ends of the same process,
that process which distinguishes man from all other animals,
and makes human civilization possible: that is, the use and
the manufacture of tools.

CHAPTER II

TYPES OF HUMAN BEHAVIOR AND THEIR SOCIAL
SIGNIFICANCE--INSTINCT, HABIT, AND EMOTION

INSTINCTIVE BEHAVIOR. We have already noted the fact that
both men and animals are equipped with a wide variety of
unlearned responses to given stimuli. In the case of human
beings, this original equipment varies from such a specific
reaction as pulling away the hand when it is pinched or burned,
to such general innate tendencies as those of herding or playing
with other people. In a later stage of this discussion we
shall examine the more important of these primary modes of
behavior. At this point our chief concern is with certain
general considerations that apply to them all.

The equipment of instincts with which a human being is at
birth endowed must be considered in two ways. It consists,
in the first place, of definite and unlearned mechanisms of
behavior, fixed original responses to given stimuli. These
are, at the same time, the original driving forces of action.
An instinct is at once an unlearned mechanism for making a
response and an unlearned tendency to make it. That is,
given certain situations, human beings do not simply utilize
inborn reactions, but exhibit inborn drives or desires to make
those reactions. There is