The term "nerves," and its adjective, "nervous," are used in two totally distinct senses: one, that which is vague and unsubstantial, purely mental or subjective, and, in the realm of disease at least, imaginary; the other, purely anatomical, referring to certain strands of tissue devoted to the purpose of transmitting impulses, and the condition affecting these strands. I am not so rash as to raise the question here,--still less to attempt to settle it,--which of these two views is the right and rational one. Whether the brain secretes thought as the liver does bile, or whether the mind created the brain and nervous system, or, as it has been epigrammatically put in a recent work on psychology, "whether the mind has a body, or the body has a mind," I merely call attention to the fact that this confusion of meanings exists, and that its injection into the field of medicine and pathology, at least, has done an enormous amount of harm in the way of confusing problems and preventing a proper recognition of the actual facts. The more carefully and exhaustively and dispassionately we study the disorders of the nervous system which come in the field of medicine, the more irresistibly we are drawn to the conclusion that from neurasthenia and hysteria to insanity and paralysis they are every one of them the result of some definite morbid change in some cell or strand of the nervous system. The man or woman who is nervous has poisoned nerve-cells, either from hereditary defect, or direct saturation of the tissues with toxic substances. The patient who has an imaginary disease is suffering from some kind of a hallucination produced by poison-soaked nerve-cells, such as in highest degree give rise to the delirium of fevers, and the horrid spectres of delirium tremens. Even the man who is suffering from a "mind diseased," and confined in one of our merciful asylums for the insane, is in that condition and position on account of physical disease, not merely of his brain, but of his entire body. The lunatic is insane, in the for once correct derivative sense of unhealthy, to the very tips of his fingers. Not merely his mind and his brain, but his liver, his stomach, his skin, his hair and fingernails, the very sweat-glands of his surface which control his bodily odor, are diseased and have been so usually for years before his mind breaks down. Tell a competent expert to pick out of a crowd of a thousand men and women the ten who are likely to become insane, and his selection will be found almost invariably to include the two or three who will actually become so.