"Chiropractic is a science of applied neurophysiologic diagnosis based on the theory of health and disease are life processes related to the function of the nervous system:  irritation of the nervous system by mechanical, chemical, or psychic factors is the cause of disease;  restoration and maintenance of health depend on the normal function of the nervous system.  Diagnosis is the identification of these noxious irritants and treatment is their removal."
                                                               -Dorland's Illustrated Medical Dictionary, 28th Ed., W.B. Saunder's Co.