Most people forget their dreams as they forget their waking thoughts. Unless some very striking idea came to my mind yesterday afternoon, I am likely to be embarrassed if some one asks me: "What were you thinking of yesterday afternoon?" We shall see in another chapter that our dream thoughts are not in any way different from our waking thoughts, and that unless they have a special meaning there is no reason why they should obsess us more than our waking thoughts do. In fact, a remembered dream is as important as an obsessive idea and has the same meaning. Thousands of futile dreams dreamt in one night may not leave a deeper impression on our "mind" than thousands of futile thoughts which flit through our consciousness in one day. Before considering the origin of dreams I must restate briefly a proposition which I have discussed at length in _Psychoanalysis and Behaviour_, the indivisibility of the human organism. The words physical and mental are lacking in any real meaning and there is no physical manifestation which it not inseparably linked with some psychic phenomenon. Emotions, secretions and attitudes may be studied separately for the sake of convenience, but in reality there cannot be any emotion which is not unavoidably accompanied by a secretion and betrayed by some attitude, nor can there be any attitude which is not accompanied by a secretion and interpreted by some emotion. This must be constantly borne in mind when we attempt to answer the question: Where do dreams come from? If dreams "come from the stomach" why should distressed minds seek refuge in them? If they are purely psychic phenomena, what relief can they afford to our dissatisfied body? We shall not deny that a full bladder may at times induce urination dreams, that a full stomach may at times conjure up anxiety visions in which heavy masses oppress us, or that long continence and the consequent accumulation of sexual products may be at times responsible for sexual dreams. What the physical theory of dreams, most scientifically and conscientiously expounded by the Scandinavian Mourly Vold, will not explain, however, is that, in one subject, a urination dream may be a pleasurable visualization of relief, leading to continued sleep and, in another, an anxiety episode, picturing frustrated gratification and ending in an unpleasant awakening. A heavy dinner may people one sleeper's visions with large animals treading his stomach, and cause another to dream of vomiting fits which relieve the pressure of food. In one sleeper, sexual desire evokes libidinous visions, in another, terrifying scenes of violence. On the other hand, the very close relation observed in thousands of cases between the sleeper's dreams and his physical condition, invalidates any theory which would revert more or less literally to the belief held in ancient times that dreams were purely psychic phenomena, visions sent by the gods.