It would run this volume to quite an impossible length if I were to attempt to give an account of anything like all the interesting dreams and dream facts, apart from those which fall under the headings I have suggested, that correspondents have been kind enough to send me. I will be content with mentioning a few of the more interesting, and first I will take one that is curiously illustrative of a fact that is well known indeed, but very interesting both on its bearing on the dream state in particular and on general psychological phenomena. Some small article had been lost - I forget now what; let us say a key - belonging to one of two sisters who were travelling together. It could nowhere be found. But one night one of the sisters dreamed that she saw the key in the pocket of her travelling bag. She told this dream, on waking, to the other. "And have you looked in the pocket?" the sister asked. "No I have not," said she "for the very good reason that there is no pocket in my travelling bag." "Well," said the other "there is a pocket in mine. I will just have a look there on the chance" - and there the key was found. The inference is that the dreamer had seen (with the eye of sense, though not with the eye of observation) the key put into the pocket.

Even when the key was so found, she had no recollection of seeing it placed there, but the brain had unconsciously recorded the sensation, in course of sleep it had stumbled on that record, and by good luck the sleeper on awaking chanced to remember the mental operation that had taken place during sleep. It is a singular and almost alarming reflection that our brains are stored with countless such records of which we know nothing, nor ever shall know unless the association of ideas or some peculiar mental state bring them to our notice. In regard to all this side of the subject Miss Cobbe writes very interestingly and suggestively in the essays on "Unconscious Cerebration" and on " Dreams," respectively, that are included in her volume named Darwinism in Morals. The dream state, with its apparently ready obedience to each suggestion arising from association of ideas, would seem to be very analogous to the state of hypnotic trance. In both there is the same suspension of the powers of reason and attention, with an increase, that is very probably a consequence, of some of those mental faculties that we are bound to deem lower.

It is also worth noting that the mental operations of the sane dreamer have a close resemblance to the operations of the waking mind of a person suffering from that kind of dementia that comes either from an in-sufficient or an excessive supply of blood in the brain. And now, to take up the argument more directly in connection with the point of view which suggested the first tentative essay, 1 would say that there seem to me to be other classes that can be added, out of the mass of correspondence that I have received, to those set down at first. Several of these, the dream of strange and beautiful scenery, the dream of death, the dream of a certain house, of acting in a story, and the dream of hearing distinctly a voice in the room, seem defined enough to suggest that nearly all the cases coming under one of these headings have a common cause. The dream within a dream and several others would seem to be of sufficiently frequent occurrence, if that were all that is required, to make them worthy a class to themselves, but probably they are produced by causes that are too complex to give the most remote hope of discovering the common stimulus in the different cases.

Although many correspondents have been kind enough to suggest causes for the different well defined and common kinds of dreams, I hardly think that any of them are wholly satisfactory; on the other hand the instances that they adduce, and of which I will set out a few, grouped under their proper headings, in Part III. of this chapter, cannot fail to be of interest and may even be of value in tracing the stimulus that gives rise to each dream of the same class. As regards the falling dream, that is first on the list, the common account given of it is that it is caused by a form of indigestion which produces pressure on the heart and consequent sending of blood to the brain with a jerk. But why this should make us imagine we are falling is still left unexplained, and I fail to see that this "explanation" puts us farther on our road. It is to be observed that when we say that we "imagine we are falling " we give a true account of the dream, but when we say we "feel as if we were falling," we give, in all probability, an untrue account. For we do not know, the great majority of us, what the sensation is of falling from a great height What happens to us in the falling dream is therefore something that gives us the impression that we imagine we should experience in falling from a height.

That is all we can say. One of my correspondents does indeed suggest that the dream is a survival from the time when we lived in trees, and a chief anxiety of our lives was the fear of falling out of them in sleep. But I am not aware that monkeys often fall from trees in their sleep; and even so we ceased being monkeys some time ago. If we analyse our impression of falling from a height we shall find, I think, that a chief factor in it is the moving upward, past our eyes, of stationary objects, as the side of the precipice, etc. If any quaint trick were to be played by our circulation, or any other influence, on our optic nerves during sleep, so as to give us this impression of things moving upwards past us, we should at once, as it seems to me, have material for the construction of the falling dream. Also it would account for the singular fact that so few (though there are exceptions) of the dreamers of the falling dream ever come to the bottom, for we may suppose that most of us are awoken by the vividness of the impression of the stationary objects going upward past our eyes.