There is no single circumstance or combination of circumstances which precipitate all clinical instances of back discomfort. This simple statement should be so obvious that one must question the finality and accuracy of the diagnostic effort in those reports which relate to large series of patients treated by one method. There is no thought of impugning the basic honesty of the reporting physician in this statement, but rather of raising the fair question of whether the "slipped disc" (or whatever the etiological diagnosis) is all that happened to produce the symptoms, and whether its removal (or whatever) is all that occurred in accomplishing clinical cure improvement. If there is doubt that the answer to both questions is in the affirmative, then serious consideration must be given to those other factors, if the medical profession is ever to be a science instead of a trade. The back structures are different from comparable structures elsewhere in the body, principally in their neurological organization and controlmthere is the specific, discrete, segmental arrangement of both sensory and motor functions of muscular and nonmuscular structures via the posterior primary rami of the spinal nerves. Coupled with this is a different mechanism of segmental innervation of the vascular and nonmuscular structures which line the vertebral canal, via the sinu-vertebral nerves. Both are modulated by higher level influences. The sinu-vertebral nerves, through the sympathetic chain, may provide an additional avenue of response which may avoid or alter the influence of higher levels. The Melzack-Wall hypothesis would seem to provide an acceptable explanation for the need to modulate nociceptive afferent stimuli before they evoke pain perception and response. Since this modulation mechanism decompensates under numerous conditions, pain perception and responses do occur. Among those responses are the alterations in normal function of the low back structures, perhaps the disastrously effective one of which is decompensation of the muscular strength necessary to accomplish the demands of daily use. This problem is not so simply solved by a handout sheet of exercises. The primary consideration is to modify or relieve pain by a careful evaluation of its source and the employment in combination of those therapeutic efforts which a logical treatment plan indicates. If these be accomplished, the final and most important consideration, then, is the improvement of neuromuscular function to the level compatible with normal activities by a carefully guided activity program. There is no method for instant reversal of the status of the decompensated heart--nor the decompensated back.