The sleeping state or the psychical change to sleep, whatsoever it be, is brought about by the child being sent to sleep or compelled thereto by fatigue, only assisted by the removal of all stimuli which might open other objects to the psychical apparatus. The means which serve to keep external stimuli distant are known; but what are the means we can employ to depress the internal psychical stimuli which frustrate sleep? Look at a mother getting her child to sleep. The child is full of beseeching; he wants another kiss; he wants to play yet awhile. His requirements are in part met, in part drastically put off till the following day. Clearly these desires and needs, which agitate him, are hindrances to sleep. Every one knows the charming story of the bad boy (Baldwin Groller's) who awoke at night bellowing out, "_I want the rhinoceros_." A really good boy, instead of bellowing, would have _dreamt_ that he was playing with the rhinoceros. Because the dream which realizes his desire is believed during sleep, it removes the desire and makes sleep possible. It cannot be denied that this belief accords with the dream image, because it is arrayed in the psychical appearance of probability; the child is without the capacity which it will acquire later to distinguish hallucinations or phantasies from reality. The adult has learnt this differentiation; he has also learnt the futility of desire, and by continuous practice manages to postpone his aspirations, until they can be granted in some roundabout method by a change in the external world. For this reason it is rare for him to have his wishes realized during sleep in the short psychical way. It is even possible that this never happens, and that everything which appears to us like a child's dream demands a much more elaborate explanation. Thus it is that for adults--for every sane person without exception--a differentiation of the psychical matter has been fashioned which the child knew not. A psychical procedure has been reached which, informed by the experience of life, exercises with jealous power a dominating and restraining influence upon psychical emotions; by its relation to consciousness, and by its spontaneous mobility, it is endowed with the greatest means of psychical power. A portion of the infantile emotions has been withheld from this procedure as useless to life, and all the thoughts which flow from these are found in the state of repression.