The distinguishing characteristics of mind are of a subjective sort; we know them only from the contents of our own consciousness.

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.

Philosophical reflection could not leave the relation of mind and spirit in the obscurity which had satisfied the needs of the naive consciousness.

The general statement that the mental faculties are class concepts, belonging to descriptive psychology, relieves us of the necessity of discussing them and their significance at the present stage of our inquiry.

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.