Physiological psychology is, therefore, first of all psychology.
The materialistic point of view in psychology can claim, at best, only the value of an heuristic hypothesis.
We speak of virtue, honour, reason; but our thought does not translate any one of these concepts into a substance.
The distinguishing characteristics of mind are of a subjective sort; we know them only from the contents of our own consciousness.
Philosophical reflection could not leave the relation of mind and spirit in the obscurity which had satisfied the needs of the naive consciousness.
The attitude of physiological psychology to sensations and feelings, considered as psychical elements, is, naturally, the attitude of psychology at large.
Now, there are a very large number of bodily movements, having their source in our nervous system, that do not possess the character of conscious actions.
The results of ethnic psychology constitute, at the same time, our chief source of information regarding the general psychology of the complex mental processes.
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.
Physiology and psychology cover, between them, the field of vital phenomena; they deal with the facts of life at large, and in particular with the facts of human life.