The diffusive wave. Every sensation produces reflex effects on the whole organism. CHAPTER XXIV. INSTINCT Its definition. Instincts not always blind or invariable. Two principles of non-uniformity in instincts: 1) Their inhibition by habits; 2) Their transitoriness. Man has more instincts than any other mammal. Reflex impulses. Imitation. Emulation. Pugnacity. Sympathy. The hunting instinct. Fear. Acquisitiveness. Constructiveness. Play. Curiosity. Sociability and shyness. Secretiveness. Cleanliness. Shame. Love. Maternal love. CHAPTER XXV. THE EMOTIONS Instinctive reaction and emotional expression shade imperceptibly into each other. The expression of grief; of fear; of hatred. Emotion is a consequence, not the cause, of the bodily expression. Difficulty of testing this view. Objections to it discussed. The subtler emotions, 468. No special brain-centres for emotion. Emotional differences between individuals. The genesis of the various emotions. CHAPTER XXVI. WILL Voluntary movements: they presuppose a memory of involuntary movements. Kinæsthetic impressions, 488. No need to assume feelings of innervation. The 'mental cue' for a movement may be an image of its visual or auditory effects as well as an image of the way it feels. Ideo-motor action. Action after deliberation. Five types of decision. The feeling of effort. Unhealthiness of will: 1) The explosive type; 2) The obstructed type. Pleasure and pain are not the only springs of action. All consciousness is impulsive. What we will depends on what idea dominates in our mind. The idea's outward effects follow from the cerebral machinery. Effort of attention to a naturally repugnant idea is the essential feature of willing. The free-will controversy. Psychology, as a science, can safely postulate determinism, even if free-will be true. The education of the Will. Hypothetical brain-schemes. CHAPTER XXVII. HYPNOTISM Modes of operating and susceptibility. Theories about the hypnotic state. The symptoms of the trance. CHAPTER XXVIII. NECESSARY TRUTHS AND THE EFFECTS OF EXPERIENCE