Physiological psychology, on the other hand, is competent to investigate the relations that hold between the processes of the physical and those of the mental life.

In Aristotle the mind, regarded as the principle of life, divides into nutrition, sensation, and faculty of thought, corresponding to the inner most important stages in the succession of vital phenomena.

On the other hand, ethnic psychology must always come to the assistance of individual psychology, when the developmental forms of the complex mental processes are in question.

The old metaphysical prejudice that man 'always thinks' has not yet entirely disappeared. I am myself inclined to hold that man really thinks very little and very seldom.

Contractile movements arise, sometimes at the instigation of external stimuli but sometimes also in the absence of any apparent external influence.

Physiological psychology is, therefore, first of all psychology.

Physiology seeks to derive the processes in our own nervous system from general physical forces, without considering whether these processes are or are not accompanied by processes of consciousness.