As followers of natural science we know nothing of any relation between thoughts and the brain, except as a gross correlation in time and space.

The terminal path may, to distinguish it from internuncial common paths, be called the final common path. The motor nerve to a muscle is a collection of such final common paths.

If it is mind that we are searching the brain, then we are supposing the brain to be much more than a telephone-exchange. We are supposing it to be a telephone-exchange along with subscribers as well.

Further study of central nervous action, however, finds central inhibition too extensive and ubiquitous to make it likely that it is confined solely to the taxis of antagonistic muscles.

Natural knowledge has not forgone emotion. It has simply taken for itself new ground of emotion, under impulsion from and in sacrifice to that one of its 'values', Truth.

If we denote excitation as an end-effect by the sign plus (+), and inhibition as end-effect by the sign minus (-), such a reflex as the scratch-reflex can be termed a reflex of double-sign, for it develops excitatory end-effect and then inhibitory end-effect even during the duration of the exciting stimulus.

That our being should consist of two fundamental elements [physical and psychical] offers I suppose no greater inherent improbability than that it should rest on one only.

With the nervous system intact the reactions of the various parts of that system, the 'simple reflexes', are ever combined into great unitary harmonies, actions which in their sequence one upon another constitute in their continuity what may be termed the 'behaviour'.

This integrative action in virtue of which the nervous system unifies from separate organs an animal possessing solidarity, an individual, is the problem before us.