There were now a whole series of questions to be answered, among the most important of them being whether there was a motive for the formation of dreams, under what conditions it took place, by what methods the dream-thoughts (which are invariably full of sense) became converted into the dream (which is often senseless), and others besides. I attempted to solve all of these problems in _The Interpretation of Dreams_,[11] which I published in the year 1900. I can only find space here for the briefest abstract of my investigation. When the latent dream-thoughts that are revealed by the analysis of a dream are examined, one of them is found to stand out from among the rest, which are intelligible and well known to the dreamer. These latter thoughts are residues of waking life (the _day’s residues_, as they are called technically); but the isolated thought is found to be an impulse in the form of a wish, often of a very repellent kind, which is foreign to the waking life of the dreamer and is consequently disavowed by him with surprise or indignation. This impulse is the actual constructor of the dream: it provides the energy for its production and makes use of the day’s residues as material; the dream which thus originates represents a situation in which the impulse is satisfied, it is the fulfilment of the wish which the impulse contains. It would not be possible for this process to take place without being favored by the presence of something in the nature of a state of sleep. The necessary mental precondition of sleep is the concentration of the ego upon the wish to sleep and the withdrawal of psychical energy from all the interests of life; since at the same time all the paths of approach to motility are blocked, the ego is also able to reduce the expenditure of energy by which at other times it maintains the repressions. The unconscious impulse makes use of this nocturnal relaxation of repression in order to push its way into consciousness with the dream. But the repressive resistance of the ego is not abolished in sleep, but merely reduced. Some of it remains in the shape of a _censorship of dreams_ and forbids the unconscious impulse to express itself in the forms which it would properly assume. In consequence of the severity of the censorship of dreams, the latent dream-thoughts are obliged to submit to being altered and softened so as to make the forbidden meaning of the dream unrecognizable. This is the explanation of _dream-distortion_, which accounts for the most striking characteristic of the manifest dream. We are therefore justified in asserting that _a dream is the (disguised) fulfilment of a (repressed) wish_. It will now be seen that dreams are constructed like neurotic symptoms: they are compromises between the demands of a repressed impulse and the resistance of a censoring force in the ego. Since they have a similar origin they are equally unintelligible and stand in equal need of interpretation.