one piercing sound, for example, that of a bell, into another of quite a different nature, say, the report of cannon. In his dream he becomes aware first of the effects, which he explains by a subsequent hypothesis and becomes persuaded of the purely conjectural nature of the sound. But how comes it that the mind of the dreamer goes so far astray when the same mind, awake, is habitually cautious, careful, and so conservative in its dealings with hypotheses? why does the first plausible hypothesis of the cause of a sensation gain credit in the dreaming state? (For in a dream we look upon that dream as reality, that is, we accept our hypotheses as fully established). I have no doubt that as men argue in their dreams to-day, mankind argued, even in their waking moments, for thousands of years: the first _causa_, that occurred to the mind with reference to anything that stood in need of explanation, was accepted as the true explanation and served as such. (Savages show the same tendency in operation, as the reports of travelers agree). In the dream this atavistic relic of humanity manifests its existence within us, for it is the foundation upon which the higher rational faculty developed itself and still develops itself in every individual. Dreams carry us back to the earlier stages of human culture and afford us a means of understanding it more clearly. Dream thought comes so easily to us now because we are so thoroughly trained to it through the interminable stages of evolution during which this fanciful and facile form of theorising has prevailed. To a certain extent the dream is a restorative for the brain, which, during the day, is called upon to meet the many demands for trained thought made upon it by the conditions of a higher civilization.--We may, if we please, become sensible, even in our waking moments, of a condition that is as a door and vestibule to dreaming. If we close our eyes the brain immediately conjures up a medley of impressions of light and color, apparently a sort of imitation and echo of the impressions forced in upon the brain during its waking moments. And now the mind, in co-operation with the imagination, transforms this formless play of light and color into definite figures, moving groups, landscapes. What really takes place is a sort of reasoning from effect back to cause. As the brain inquires: whence these impressions of light and color? it posits as the inducing causes of such lights and colors, those shapes and figures. They serve the brain as the occasions of those lights and colors because the brain, when the eyes are open and the senses awake, is accustomed to perceiving the cause of every impression of light and color made upon it. Here again the imagination is continually interposing its images inasmuch as it participates in the production of the impressions made through the senses day by day: and the dream-fancy does exactly the same thing--that