Injury to other tissues, unless the injury also involves nerve tissue, is quickly repaired and the body goes on without disease. Or the injury is sufficient at once to render the body untenable and death ensues. Few pathological changes follow trauma unless nerve tissue be injured. This theory to be logical must and does include the entire nerve system. Also, since it is noted that each nerve cell presides over the nutrition of its own processes and possesses its own power of repair, it follows that unless an injury be of fatal nature or of permanent duration, even injuries to nerves tend toward automatic cure. We must seek a permanently operating interference with nerve tissue. The brain, enclosed within the comparatively solid cranium, is so well protected that nothing except fracture of the skull, violent concussion, or shutting off of its blood supply from without, will produce permanent change there. Also, unless there be pressure by foreign substance against the brain, an injury will be repaired in time and the body resume its normal functional activity. It has been demonstrated that comparatively few diseases occur in this way. Such as do are called traumatic; i. e., caused by wound or injury. In the broadest sense all disease is caused by trauma, as we shall presently show. The upper or cephalic peripheral nerves, called cranial, leave the skull by foramina in its base (except the auditory) and are so protected by the immobility of the bones of the skull as to be comparatively free from direct injury. Peripheral injuries occur to cranial nerves but are repairable; even section of the trigeminal for neuralgia is usually followed after an interval by a reunion of the severed parts. As will be shown later, the special end organs of the cranial nerves are not free from the effects of spinal subluxation and their nuclei (deep origins) often share in morbid changes in the brain tissue due to nutritional disturbances. The sympathetic portion of the nervous system might be classed with the cranial as regards infrequency of permanent interference were it not for the proximity of the great gangliated cord to the transverse processes and bodies of the vertebrae. This proximity renders it liable to sustain permanent impingement in vertebral subluxation. Trauma Affects Spinal Nerves With the exception of the first pair of Cervical nerves and the Sacral and Coccygeal, all spinal nerves pass through foramina of exit which are composed each of two movable vertebrae. The Chiropractic hypothesis is based upon the discovery that in addition to the part these vertebrae may take in general movements of the spine it is possible that their relation to each other may be changed by the application of force from without, and that this change once produced tends to remain permanently. These permanent vertebral subluxations occur with great frequency, a fact clinically demonstrable by palpation and by the X-Ray.