CLASSES OF ACTS OR RESPONSE.--Movements or acts, like other phenomena,
do not just happen. They never occur without a cause back of them.
Whether they are performed with a conscious end in view or without it,
the fact remains the same--something must lie back of the act to account
for its performance. During the last hour, each of us has performed many
simple movements and more or less complex acts. These acts have varied
greatly in character. Of many we were wholly unconscious. Others were
consciously performed, but without feeling of effort on our part. Still
others were accomplished only with effort, and after a struggle to
decide which of two lines of action we should take. Some of our acts
were reflex, some were chiefly instinctive, and some were volitional.
