Now, we do not see any essential difference between the effort of attention and what may be The intensity called the effort of psychic tension: acute desire, uncontrolled anger, passionate love, violent hatred. Each of these states may be reduced, we believe, to a system of muscular contractions co-ordinated by an idea; but in the case of attention, it is the more or less reflective idea of knowing; in the case of emotion, the unreflective idea of acting. The intensity of these violent emotions is thus likely to be nothing but the muscular tension which accompanies them. Darwin has given a remarkable description of the physiological symptoms of rage. "The action of the heart is much accelerated.... The face reddens or may turn deadly pale. The respiration is laboured, the chest heaves, and the dilated nostrils quiver. The whole body often trembles. The voice is affected. The teeth are clenched or ground together and the muscular system is commonly stimulated to violent, almost frantic action. The gestures ... represent more or less plainly the act of striking or fighting with an enemy."[8] We shall not go so far as to maintain, with Professor James,[9] that the emotion of rage is reducible to the sum of these organic sensations: there will always be an irreducible psychic element in anger, if this be only the idea of striking or fighting, of which Darwin speaks, and which gives a common direction to so many diverse movements. But, though this idea determines the direction of the emotional state and the accompanying movements, the growing intensity of the state itself is, we believe, nothing but the deeper and deeper disturbance of the organism, a disturbance which consciousness has no difficulty in measuring by the number and extent of the bodily surfaces concerned. It will be useless to assert that there is a restrained rage which is all the more intense. The reason is that, where emotion has free play, consciousness does not dwell on the details of the accompanying movements, but it does dwell upon them and is concentrated upon them when its object is to conceal them. Eliminate, in short, all trace of organic disturbance, all tendency towards muscular contraction, and all that will be left of anger will be the idea, or, if you still insist on making it an emotion, you will be unable to assign it any intensity. [Sidenote: Intensity and reflex movements. No essential difference between intensity of deep-seated feelings and that of violent emotions.]