Physiological psychology is, therefore, first of all psychology.

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.

The old metaphysical prejudice that man 'always thinks' has not yet entirely disappeared. I am myself inclined to hold that man really thinks very little and very seldom.

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.

Some say that everything that is called a psychical law is nothing but the psychological reflex of physical combinations, which is made up of sensations joined to certain central cerebral processes... It is contradicted by the fact of consciousness itself, which cannot possibly be derived from any physical qualities of material molecules or atoms.

Now the word-symbols of conceptual ideas have passed so long from hand to hand in the service of the understanding, that they have gradually lost all such fanciful reference.

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.