The Machinery of the Mind

In order to arrive at an adequate understanding of mental processes it is necessary to have some idea of the machinery whereby the mind makes contact with the body.

Throughout every inch of our organism is a network of specialised fibres whose function it is to carry nervous impulses from the sense organs to the central nervous system of brain and spinal cord, and from thence out again to the muscles, glands, and other organs of reaction. The sense organs act as receivers of sensation, the nerve fibres as transmitters, the central nervous system as a general telephone exchange, and the muscles, glands, and organs as the executants of the impulses of the mind.

Sense organs consist of cells, or sets of cells, specialised for the reception of particular kinds of impressions. That is to say, if the particular kind of stimulus they are fitted to receive is administered to them, a change, probably of a chemical type, takes place in their substance, which, it is thought, gives rise to energy of an electrical nature, which runs along the nerve fibre as along a wire. At the present moment, however, our knowledge of the nature of the nervous impulse is tentative and hypothetical.