Evidently, then, in the subjects of tic the _impulse to seek a sensation_ is of very common occurrence, as is also the _impulse to repeat to excess a functional act_. It is precisely this exaggerated and inopportune multiplication of movement that is pathological. The mother of one of Noir's patients was always tempted to repeat any simple purposive movement that she had made a moment before, even though the reason for the act no longer existed. The imperiousness of these impulses, and the peculiar relief attendant on submission to them, accentuate the closeness of the resemblance between tic and obsession, to which reference will be made later; but it is necessary at this early stage to indicate the bearing of these psychical phenomena on the pathogeny and diagnosis of tic. Many of the conditions with which we are dealing are characterised in addition by an emotional element. Dupré[13] believes an emotional shook is the exciting cause of tic, as it sometimes is of obsessions. Apropos of this view, we may quote again from the history of the young patient J.: During his holidays he improved sufficiently to enable him to resume his classes, but another attack of influenza in the beginning of 1900 was the occasion of a relapse. He began to complain of overpowering fatigue; became depressed and morbidly anxious about his future; had attacks of hysterical sobbing; suffered great mental anguish, accompanied by flushing and profuse perspiration; in short, he fell into a veritable state of _mal obsédant_. At the same time, the slightest pain or annoyance was a pretext for his tics to exhibit themselves with redoubled vigour. Even the mere idea of his tics, the fear of them, incited him further in the same direction. He seems then to have set himself to invent new movements, and forgetting forthwith that he himself was their creator, became alarmed at them as sure signs of the aggravation of his disease. Analogous details will be found in all cases which have been studied as well from the mental as from the physical side. For our part, we consider a tic cannot be a tic unless it be associated with a certain degree of mental instability and imperfection, indubitable evidence of which is furnished by a psychical abnormality of constant occurrence in this malady--viz. anomalies of volition. TIC AND WILL. It might be imagined that a tic would cease to exist as such were a voluntary element to enter into its constitution. The fact, however, that tic is the sequel to frequent repetition of a primarily voluntary act, and that it may be arrested, transformed, or aborted, is proof to the contrary of which there is no gainsaying.