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.

From the standpoint of observation, then, we must regard it as a highly probable hypothesis that the beginnings of the mental life date from as far back as the beginnings of life at large.

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.

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.

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.

Physiological psychology is, therefore, first of all psychology.

Child psychology and animal psychology are of relatively slight importance, as compared with the sciences which deal with the corresponding physiological problems of ontogeny and phylogeny.