But a careful observer should have no difficulty in discovering that a dream is not entirely severed from the continuity of the conscious, for in almost every dream certain details are found which have their origin in the impressions, thoughts, or states of mind of one of the preceding days. In so far a certain continuity does exist, albeit a _retrograde_ one. But any one keenly interested in the dream problem cannot have failed to observe that a dream has also a _progressive_ continuity--if such an expression be permitted--since dreams occasionally exert a remarkable influence upon the conscious mental life, even of persons who cannot be considered superstitious or particularly abnormal. These occasional after-effects are usually seen in a more or less distinct change in the dreamer's frame of mind. It is probably in consequence of this loose connection with the other conscious contents, that the recollected dream is so extremely unstable. Many dreams baffle all attempts at reproduction, even immediately after waking; others can only be remembered with doubtful accuracy, and comparatively few can be termed really distinct and clearly reproduceable. This peculiar reaction with regard to recollection may be understood by considering the characteristics of the various elements combined in a dream. The combination of ideas in dreams is essentially _phantastic_; they are linked together in a sequence which, as a rule, is quite foreign to our current way of thinking, and in striking contrast to the logical sequence of ideas which we consider to be a special characteristic of conscious mental processes. It is to this characteristic that dreams owe the common epithet of "meaningless." Before pronouncing this verdict, we must reflect that dreams and their chains of ideas are something that _we_ do not understand. Such a verdict would therefore be merely a projection of our non-comprehension upon its object. But that would not prevent its own peculiar meaning being inherent in a dream. In spite of the fact that for centuries endeavours have been made to extract a prophetic meaning from dreams, Freud's discovery is practically the first successful attempt to find their real significance. His work merits the term "scientific," because he has evolved a technique which, not only he, but many other investigators also assert achieves its object, namely, the understanding of the meaning of the dream. This meaning is not identical with the one which the manifest dream content seems to indicate. This is not the place for a critical discussion of Freud's psychology of dreams. But I will try to give a brief summary of what may be regarded as more or less established facts of dream psychology to-day. The first question we must discuss is, whence do we deduce the justification for attributing to dreams any other significance than the one indicated in the unsatisfying fragmentary meaning of the manifest dream content?