mental states, the more intelligible does our inner life become to us. Especially is this true of certain curious phenomena to which our current psychology pays little attention—those of automatism, suggestibility, and double consciousness as seen in hypnosis, spirit-writing, trance speech, et id genus omne. Not that we are yet in position to explain these phenomena in detail. There is much that defies analysis at our present stage of knowledge, but I have no hesitation in saying that in these dynamic conceptions we have found the key which will in time solve these and many other psychological riddles.
We know little or nothing of what happens in the brain while we live and move and have our being. In the early days of experimental psychology the physical bases of mental states were crudely conceived as gross movements, either of the nerves themselves or of some fluid supposed to flow along the nerves and veins to the brain and heart. Nowadays these simpler conceptions are displaced by theories of chemical activities or molecular vibrations of some kind. For my own part, I am sometimes inclined to suspect that the true physical basis is none of these, but a disturbance of the same medium that transmits light and heat—the ether—and to regard the cellular and fibrous structures of the nervous system as a mechanism for producing and transmitting these disturbances, much as the battery and wires of an electric circuit produce and transmit that mode of ethereal disturbance which we call electricity. However this may be, it is quite certain that the processes which take place in the nervous system are all of one order and are analogous to—nay, a part of—the physical transformations of energy which we see in the outer world. Their proximate source is the stored-up molecular energy of the food we eat; they are disengaged by the operation of external and internal stimuli; they can re-enforce or destroy one another; they can produce extensive muscular, secretory, and nutritive changes in the body.
Although all of these processes are of essentially the same order in that all taken together form one system of forces, the constitution of every part of which depends for its character upon the constitution of all the coexisting parts, it is probable that consciousness is not connected with every part of the system, but only with those processes that take place in the cortex—that is, the outer layer of gray matter that covers the surface of the brain. At every moment of conscious life the cortex is the scene of activities so delicate and complex that we can never hope to frame an adequate conception of them. The masses of cells are forever disengaging pulse after pulse of molecular or ethereal disturbance, probably of a vibratory character; by the countless systems of interlacing fibers these pulses are transmitted from
