We know, from ordinary life, that we are not able to direct our attention perfectly steadily and uniformly to one and the same object... At times the attention turns towards the object most intensely, and at times the energy flags.

If we take an unprejudiced view of the processes of consciousness, free from all the so-called association rules and theories, we see at once that an idea is no more an even relatively constant thing than is a feeling or emotion or volitional process. There exist only changing and transient ideational processes ; there are no permanent ideas that return again and disappear again.

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

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

Thus ordered thinking arises out of the ordered course of nature in which man finds himself, and this thinking is from the beginning nothing more than the subjective reproduction of the regularity according to the law of natural phenomena. On the other hand, this reproduction is only possible by means of the will that controls the concatenation of ideas.

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.