In dreams, time and the limitations of space are apparently annihilated. This is to be explained by the fact that the reports of the senses and tha movements of external bodies by which we measure time are shut out, and the mind is entirely absorbed in a series of images.

I entered the South Kensington Museum in London, and saw a painting of an Alderney bull, cow, and calf in a field, which produced so extraordinary an illusion that I advanced several steps toward it in broad daylight, under the belief that I was looking out of a window into the park. The same phenomenon occurs under the spell of an orator of the highest grade; and it is the charm of a theatrical performance to make an audience think and feel that a series of events which would ordinarily occupy many years is taking place before them. That which, under these circumstances, is accomplished in part by abstraction or external means, in dreams is done entirely by cutting off all possibility of estimating time or space.

The mind is supposed to move more rapidly in dreams than in waking thoughts. Dreams without doubt are more diversified and numerous than the waking thoughts of busy men and women absorbed in a particular routine of work, or in the necessary cares of the body, or in conversation circumscribed by conventional laws, the slow rate of speech, and the duty of listening. But it is an error to think that dream-images are more numerous than those of revery. In a single hour of revery one may see more images than he could fully describe in a volume of a thousand pages. It is as true of the waking as of the dreaming state, that Lulled in the countless chambers of the brain, Our thoughts are linked in many a hidden chain ; Wake but one, and lo! what myriads rise : Each stamps its image as the other flies.

Apparent loss of identity in dreams, and finding one's self in impossible positions, are the result of the entire occupation of the perceptive faculties with one image at a time. A dream that a man is a clergyman may change into one that he is a general commanding on the field of battle, and he will see no incongruity. He may even imagine himself to be two persons at the same time, as in Dr. Johnson's case when he contended with a man, and was much chagrined to feel that his opponent had the better of him in wit. He was consoled, however, when on waking he perceived that he had furnished the wit for both.

The vividness of dreams is to he explained in the same way. If a man sees that his own house is on fire, and his family in danger, he looks at the scene in such a way that he becomes for the time as unconscious of anything else as though there were nothing in his brain but the picture. So in the dream, as he sees nothing but the picture, it must be more vivid than any ordinary reality can possibly be; only from the most extraordinary scenes can an analogy be drawn.

In dreams circumstances often appear which had been known by the dreamer, but practically forgotten. Men have sworn that they never knew certain things, and maintained that they had been revealed to them in dreams, when subsequent investigation proved indubitably that they had known, but had forgotten them. The recurrence is precisely like ordinary waking experiences. Events which have not emerged into consciousness for a score of years, or longer, and phrases, parts of words, expressions of countenance, tones of voices, analogies stumbled upon in the most out-of-the-way places, may in a single moment bring an entire scene with several series of related events before the mind.

The testimony of the mind excited to a certain degree of activity by fear of death by shipwreck or fire, or, as Whymper has shown in his " Scrambles among the Alps," the immediate expectation of a fatal fall, is that it seems to see at a glance the whole of the past life. This is sufficient to show what it can do in an entirely normal state, and nothing can ever occur in dreams more vivid than this, though it is to be considered that we have only the statements of these persons in regard to what they think was their mental condition ; nor in any case could they know that they saw everything.

Wheu one dreams that he is dreaming, which occasionally occurs, he is approaching the waking state; but since he cannot at that time sit in judgment fully on what he dreams without waking, it is equally clear that his state resembles that of a delirious person who may perceive that he is delirious and acknowledge it, but in a few seconds be again absorbed in what he sees.

Some of the most interesting achievements of the mind in dreams are the composition of poetry and the working out of mathematical problems. Dr. Aber-crombie says that his friend Dr. Gregory told him that thoughts and even expressions which had occurred to him in dreams seemed to him so good when he awoke that he used them in his college lectures. Condorcet, having gone to bed before finishing certain profound calculations, said afterward that sometimes the conclusions of the work had been revealed to him in dreams. Dr. Abercrombie relates that Benjamin Franklin, than whose a more well-balanced and self-controlled mind never existed, assured Cabanis that the bearing and issue of political events which puzzled him when awake were not unfrequently unfolded to him in his dreams. Dr. Carpenter attempts to explain this by the theory well known as " unconscious cerebration." Like the terms of the phrenologists, this may describe but does not explain the process; and what it describes occurs frequently while we are awake. Not only in questions of memory, but in the profoundest thought, how often, when we have been compelled to turn from one class of work to another, and are, so far as our consciousness reports, en-tirely absorbed in it, in an instant a thought germane to the first problem which was occupying the mind appears with such clearness as to surpass in pertinency and value anything which wc had previously reached. We are compelled to take note of it, and in the case of defective recollection the best of all modes is to cease to think about the matter, and in a short time it will appear almost with the intelligence of a messenger bringing something for which he had been sent.