From the original concussion of forces which produces a nerve-impigning subluxation to the stage of chronic disease with which the patient usually approaches the Chiropractor for relief, disease develops by a series of gradual steps. Successive changes take place from time to time in the degree of subluxation as it is augmented by further jars, strains, etc., or by the reaction of secondary causes upon it and with these changes come corresponding changes in the development of the disease. Perhaps the first effect of the bad subluxation is irritation of a nerve and acute functional disturbance such as pain, fever, etc. The later effect may be paralysis and its attendant train of evils. When the Chiropractor begins adjustment he does not at once return the long-displaced and misshapen vertebra to its normal position. He merely _tends_ to do so, his adjustments making slight and gradual changes from the abnormal back to normal. Thus it is that the subluxation passes back in reverse order through the successive stages of its development, following a process which may be called the involution of the subluxation. At the same time the morbid process resulting from the subluxation tends to retrace its steps, passing in reverse order through the stages by which it developed. Pains which have not been felt for years may unaccountably return under the reawakening of the long dormant nerves. Headache, long absent but once a prominent feature of the disease, may again make its appearance. The patient _feels_ worse. These changes, however, take place much more rapidly during the correction than during the development of the disease. To a certain extent they are probably always present, although in many cases they occur so rapidly or are modified so much by changed environment as to be unrecognizable. In many cases it is possible by securing an accurate history and by careful observation of the patient’s progress to observe a definite reappearance, in reverse order, of every important event in the history of the disease. For instance, if the patient has at one time had a severe fever, perhaps lasting many weeks, and has later developed a chronic weakness marking the increase in degree of subluxation, the fever may reappear during adjustments, last a day or two, and disappear forever, having been corrected beyond that stage.