It is characteristic that dreams never express themselves in this logical, abstract way but always in the language of parable and simile. This is also a characteristic of primitive languages, whose flowery turns of phrase are very striking. If we remember the monuments of ancient literature, we find that what nowadays is expressed by means of abstractions was then expressed mostly by similes. Even a philosopher like Plato did not disdain to express certain fundamental ideas in this way.

Just as the body bears the traces of its phylogenetic development, so also does the human mind. Hence there is nothing surprising about the possibility that the figurative language of dreams is a survival from an archaic mode of thought.

At the same time the theft of the apple is a typical dream-motif that occurs in many different variations in numerous dreams. It is also a well-known mythological motif, which is found not only in the story of the Garden of Eden but in countless myths and fairytales from all ages and climes. It is one of those universally human symbols which can reappear autochthonously in any one, at any time. Thus dream psychology opens the way to a general comparative psychology rom which we may hope to gain the same understanding of the development and structure of the human psyche as comparative anatomy has given us concerning the human body.

Dreams, then, convey to us in figurative language–that is, in sensuous, concrete imagery–thoughts, judgments, views, directives, tendencies, which were unconscious either because of repression or through mere lack of realization. Precisely because they are contents of the unconscious, and the dream is a derivative of unconscious processes, it contains a reflection of the unconscious contents. It is not a reflection of unconscious contents in general but only of certain contents, which are linked together associatively and are selected by the conscious situation of the moment. I regard this observation as a very important one in practice. If we want to interpret a dream correctly, we need a thorough knowledge of the conscious sirtuation at that moment, because the dream contains its unconscious complement, that is, the material which the conscious situation has constellated in the unconscious. Without this knowledge it is impossible to interpret a dream correctly, except by a lucky fluke.

As a rule, the unconscious content contrasts strikingly with the conscious material, particularly when the conscious attitude tends too exclusively in a direction that would threaten the vital needs of the individual. The more one-sided his conscious attitude is, and the further it deviates from the optimum, the greater becomes the possibility that vivid dreams with a strongly contrasting but purposive content will appear as an expression of the self-regulation of the psyche.

Just as the body reacts purposively to injuries or infections or any abnormal conditions, so the psychic functions react to unnatural or dangerous disturbances with purposive defense-mechanisms. Among these purposive reactions we must include the dream, since it furnishes the unconscious material constellated in a given conscious situation and supplies it to consciousness in symbolical form. In this material are to be found all those associations which remained unconscious because of their feeble accentuation but which still possess sufficient energy to make themselves perceptible in the sleeping state.

Naturally the purposive nature of the dream-content is not immediately discernible from outside without further investigation. An analysis of the manifest dream-content is required before we can get at the really compensatory factors in the latent dream-content. Most of the physical defense-mechanisms are of this non-obvious and, so to speak, indirect nature, and their purposiveness can be recognized only after careful investigation. I need only remind you of the significance of fever or of suppuration processes in an infected wound.

The process of psychic compensation are almost always a very individual nature, and this makes the task of proving their compensatory character considerably more difficult. Because of this peculiarity, it is often very difficult, especially for the beginner, to see how far a dream-content has a compensatory significance.