That the Chiropractic theory, or more properly the subluxation theory, does not include all of the etiology of disease is evidenced by the facts of contagion and infection, by the effect upon the organism of the introduction of poison, by the consequences of worry, anger, and other abnormal mental states and conditions. These facts do not in the least invalidate the theory. They merely require explanation which will make clear their relation to the subluxation. That such explanation is abundantly at hand strengthens the position of Chiropractic more than would negation of all other causes save the one we concentrate upon. The Mentalist who holds that all diseases exist in and are but figments of the mind is as far afield as the Physicist who holds that special nerve energy is nonexistent. The Chiropractor views Man as a complex psycho-physical unit, self-operating and internally self-healing until environmental forces disturb the nice adjustment of the machinery. Disease is produced by, and is, a series of events, chief and most permanent of which is the subluxation. We may consider its etiology according to the order in which the events take place thus: Direct Chain Concussion of Forces. Subluxation of Vertebra. Impingement of Nerve. Excitation or Inhibition. Disease--Abnormal Function. Accessory Chains Between the last two steps above, or following the last, are often introduced one or more of the following accessory chains which modify or increase the final effect and are themselves made possible by the first four steps in the direct chain. Pathogenic germ. Poisonous excretions from germs. Tissue destruction by chemical action of such toxins. Reflex muscular tension tending to increase subluxation and thus augment nerve impingement and its effects. Or Dietetic error. Abnormal chemical action. Tissue destruction or nerve irritation by chemical poisons. Reflex motor disturbances which further limit digestive power. Or Abnormal mental condition. Waste of nerve energy with production of toxins. General metabolic disturbance. Increased disease wherever disease previously existed. These are offered merely as illustrations. There are many accessory chains which aid in the production or development of disease and act as _secondary causes_. Concussion of Forces