but that one has merely been thinking in a peculiar manner- dreaming- occurs to us only on waking. It is this characteristic which distinguishes the genuine dream from the day-dream, which is never confused with reality.

The characteristics of the dream-life thus far considered have been summed up by Burdach (p. 476) as follows: "As characteristic features of the dream we may state (a) that the subjective activity of our psyche appears as objective, inasmuch as our perceptive faculties apprehend the products of phantasy as though they were sensory activities... (b) that sleep abrogates our voluntary action; hence falling asleep involves a certain degree of passivity... The images of sleep are conditioned by the relaxation of our powers of will."

It now remains to account for the credulity of the mind in respect to the dream-hallucinations which are able to make their appearance only after the suspension of certain voluntary powers. Strumpell asserts that in this respect the psyche behaves correctly and in conformity with its mechanism. The dream- elements are by no means mere representations, but true and actual experiences of the psyche, similar to those which come to the waking state by way of the senses (p. 34). Whereas in the waking state the mind thinks and imagines by means of verbal images and language, in dreams it thinks and imagines in actual perceptual images (p. 35). Dreams, moreover, reveal a spatial consciousness, inasmuch as in dreams, just as in the waking state, sensations and images are transposed into outer space (p. 36). It must therefore be admitted that in dreams the mind preserves the same attitude in respect of images and perceptions as in the waking state (p. 43). And if it forms erroneous conclusions in respect of these images and perceptions, this is due to the fact that in sleep it is deprived of that criterion which alone can distinguish between sensory perceptions emanating from within and those coming from without. It is unable to subject its images to those tests which alone can prove their objective reality. Further, it neglects to differentiate between those images which can be exchanged at will and those in respect of which there is no free choice. It errs because it cannot apply the law of causality to the content of its dreams (p. 58). In brief, its alienation from the outer world is the very reason for its belief in its subjective dream-world.

Delboeuf arrives at the same conclusion through a somewhat different line of argument. We believe in the reality of dream-pictures because in sleep we have no other impressions with which to compare them; because we are cut off from the outer world. But it is not because we are unable, when asleep, to test our hallucinations that we believe in their reality. Dreams can make us believe that we are applying such tests- that we are touching, say, the rose that we see in our dream; and yet we are dreaming. According to Delboeuf there is no valid criterion that can show whether something is a dream or a waking reality, except- and that only pragmatically- the fact of waking. "I conclude that all that has been experienced between falling asleep and waking is a delusion, if I find on waking that I am lying undressed in bed" (p. 84). "I considered the images of my dream real while I was asleep on account of the unsleeping mental habit of assuming an outer world with which I can contrast my ego." *

* Haffner, like Delboeuf, has attempted to explain the act of dreaming by the alteration which an abnormally introduced condition must have upon the otherwise correct functioning of the intact psychic apparatus; but he describes this condition in somewhat different terms. He states that the first distinguishing mark of dreams is the abolition of time and space, i.e., the emancipation of the representation from the individual's position in the spatial and temporal order. Associated with this is the second fundamental character of dreams, the mistaking of the hallucinations, imaginations, and phantasy-combinations for objective perceptions. "The sum-total of the higher psychic functions, particularly the formation of concepts, judgments, and conclusions on the one hand, and free self-determination on the other hand, combine with the sensory phantasy-images, and at all times have these as a substratum. These activities too, therefore, participate in the erratic nature of the dream-representations. We say they participate, for our faculties of judgment and will are in themselves unaltered during sleep. As far as their activity is concerned, we are just as shrewd and just as free as in the waking state. A man cannot violate the laws of thought; that is, even in a dream he cannot judge things to be identical which present themselves to him as opposites. He can desire in a dream only that which he regards as a good (sub ratione boni). But in this application