ABSTRACT
The development of physics has aggravated and intensified the problem of Mind and Body by stripping the material object of all secondary qualities which make up the content of philosophers’ sense-perception, and are attributed by common sense to an external reality. The men who fixed the outlines of the standard philosophy of physics answered with some confidence “To the mind.” The materialist philosopher, if he accepts the account of the matter, must deny that anything present in experience forms part of the physical world. Psychologists have to rely for much of their information on introspection, on the accounts which men give of what passes through their consciousness. Consciousness is a property of certain complex material objects—namely, animal organisms. The movements of masses in space, which are the causes of everything else in the world, also cause the states of consciousness of men and other animals.
