Physiology is concerned with all those phenomena of life that present them selves to us in sense perception as bodily processes, and accordingly form part of that total environment which we name the external world.

The animal kingdom exhibits a series of mental developments which may be regarded as antecedents to the mental development of man, for the mental life of animals shows itself to be throughout, in its elements and in the general laws governing the combination of the elements, the same as the mental life of man.

Psychology must not only strive to become a useful basis for the other mental sciences, but it must also turn again and again to the historical sciences, in order to obtain an understanding for the more highly developed metal processes.

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

The task of physiological psychology remains the same in the analysis of ideas that it was in the investigation of sensations: to act as mediator between the neighbouring sciences of physiology and psychology.

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

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