ed to explain civilization and progress as
phenomena due to the interaction and association of human beings, rather
than to any fundamental changes in human nature itself. In other words,
the difference between a savage and a civilized man is not due to any
fundamental differences in their brain cells but to the connections and
mutual stimulations which are established by experience and education
between those cells. In the savage those possibilities are not absent
but latent. In the same way the difference between the civilization of
Central Africa and that of Western Europe is due, not to the difference
in native abilities of the individuals and the peoples who have created
them, but rather to the form which the association and interaction
between those individuals and groups of individuals has taken. We
sometimes attribute the difference in culture which we meet among races
to the climate and physical conditions generally, but, in the long run,
the difference is determined by the way in which climate and physical
condition determine the contacts and communications of individuals.

So, too, in the corporate life of the individual man it is the
association of the nerve cells, their lines of connection and
communication, that is responsible for the most of the differences
between the ignorant and the educated, the savage and civilized man. The
neurone, however, is a little unicellular animal, like the amoeba or the
paramecium. Its life consists of: (1) eating, (2) excreting waste
products, (3) growing, (4) being sensitive, and (5) movement, and, as
Thorndike expresses it: "The safest provisional hypothesis about the
action of the neurones singly is that they retain the modes of behavior
common to unicellular animals, so far as consistent with the special
conditions of their life as an element of man's nervous system."

In the widest sense of the term, behavior may be said to include all the
chemical and physical changes that go on inside the organism, as well as
every response to stimulus either from within or from without the
organism. In recent studies of animal behavior, however, the word has
acquired a special and technical meaning in which it is applied
exclusively to those actions that have been, or may be, modified by
conscious experience. What the animal does in its efforts to find food
is behavior, but the processes of digestion are relegated to another
field of observation, namely, physiology.

In all the fo