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.

There are other sources of psychological knowledge, which become accessible at the very point where the experimental method fails us.

In the animal world, on the other hand, the process of evolution is characterised by the progressive discrimination of the animal and vegetative functions, and a consequent differentiation of these two great provinces into their separate departments.

Our mind is so fortunately equipped, that it brings us the most important bases for our thoughts without our having the least knowledge of this work of elaboration. Only the results of it become unconscious.

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 results of ethnic psychology constitute, at the same time, our chief source of information regarding the general psychology of the complex mental processes.