The nervous exaltation so produced may be the effect of the rapid repetition of stimuli acting as repetition acts, for instance, when it produces seasickness or tickling.... If the exaltation is extreme conscious control of feeling and action is diminished.[65] Reaction is narrowed and men may behave, as they behave in dreams, less rationally and morally than they do if the whole of their nature is brought into play.[66] [65] M. Dide, a French psychologist, regards "the hypnosis produced by emotional shock--and this occurs not only in war but in other great catastrophies as well--as genetically a defence reaction, like natural sleep whose function according to him is primarily prophylactic against exhaustion and fatigue, ... it is comparable to the so-called death-shamming of animals." (Dide, M., _Les emotions et la guerre_ (Paris, 1918), Review of, _Psychological Bulletin_, vol. xv, no. 12, Dec., 1918, p. 441.) [66] Wallas, Graham, _The Great Society_ (N. Y., 1917), p. 136. What Wallas has said of the additional stimulation which the presence of a crowd induces may be given wider application, and is indeed a most illuminating thought, describing exactly the psycho-emotional reactions produced by the stimulation of terrifying scenes, such as were witnessed at Halifax. A case in point was that of the nervous exaltation produced upon a young doctor who operated continuously for many hours in the removal of injured eyes. The emotional tension he went through is expressed in his words to a witness: "If relief doesn't come to me soon, I shall murder somebody." Another instance where conscious control of feeling and action was diminished was that of a soldier. He was so affected by what he passed through during the explosion and his two days' participation in relief work, that he quite unwittingly took a seat in a train departing for Montreal. Later in a hospital of that city after many mental wanderings he recovered his memory. Over and over again he had been picturing the dreadful scenes which he had experienced. This condition includes a hyperactivity of the imagination "characterized by oneirism [oneiric delirium] reproducing most often the tragic or terrible scenes which immediately preceded the hypogenic shock."[67] [67] _Ibid._, p. 440.