Our memories tend to fall into groups or systems. We all possess a great number of such systematised groups of impressions. Every period of life, every subject we have occupied ourselves with, every intimate friend we have had, each represents a more or less separate mass of ideas and feelings. Within each system one idea or feeling easily calls up another belonging to the same system. Moreover, in full and alert waking life, each system is in touch with the systems related to it. If there crowd into the field of consciousness the memories belonging to one period of life, or one country we have lived in, we can control and criticise those memories by reference to others belonging to another period or another country. If we are overwhelmed by the thoughts and emotions associated with the memory of one friend we can restore our mental balance by evoking the thoughts and emotions associated with another friend. The various systems are in this way co-ordinated in apperception.[177]
In sleep, however, these groups are not usually so firmly held together by the cords along which we can move in our waking moments from one to the other. They are, as it were, loosened from their moorings, and on the sea of sleeping consciousness they drift apart or jostle together in new and what seem to be random associations. This is that process of dissociation which we find so marked in dreaming, and in all those psychic phenomena—hallucinations, hysteria, multiple personality, insanity—which are allied to dreaming.
A simple illustration of the clash and confusion of two opposing systems of memories in dreams, when due apperceptive control is lacking, is supplied by a common and well-recognised type of dream, the dream of returning to the school of youth.[178] Many people are occasionally liable to this dream, which is often vivid and disturbing. We may have left the schoolroom thirty years or more ago, and never seen it since; it may have vanished from our waking thoughts. Yet from time to time we find ourselves there in our dreams, and called upon to take our old place, always with a sense of conflict, a vague discomfort, a feeling of something incongruous and humiliating, for we realise that we are now too old. Here is a dream in illustration: I find myself back at my old school, but my old schoolmaster is not there; he is away ill, as I am told by his substitute, whose face somehow seems familiar, though I cannot recall where I have seen it. I do not know any of the boys; I am returning after an absence of some months. I realise that I am to take my old place again, and yet I feel a profound repulsion to do so, a sense that it is somehow incongruous. This latter feeling seems to prevail, for I finally assume the part of a visitor, and remark, insincerely, to the master that it is pleasant to see the old place again.
In such a case as this it seems that a picture from an ancient system of memories floats across the field of sleeping consciousness, and the dreamer is naturally drawn into that system and begins to adapt himself to its demands. But, as he does so, the influence of other later and incompatible systems of memories begins unconsciously to affect the dreamer.[179] The cords of connection, however, which when awake would enable him to adjust critically the opposing systems, are not acting; apperception is defective. Yet the opposing systems are there, outside the immediate field of consciousness, and jostling the ancient system which has come into the central focus. Finally this jostling of the ancient system by more recent systems causes a harmonising modification in consciousness. The dreamer ceases to be a boy in his old school, and assumes the part of a visitor.
Dreams of our recently dead friends furnish a type of dream which is formed in exactly the same way as these dreams of a return to school life. The only difference is that they often present it in a more vivid, pronounced, and poignantly emotional shape. This is so, partly from the very subject of such dreams, and partly because the fact of death definitely divides our impressions of our dead friends into two groups, which are intimately allied to each other by their subject, and yet absolutely opposed by the fact that in the one group the friend is alive, and in the other dead.
I proceed to present two series of dreams—one in a man, the other in a woman—illustrating this type of dream.[180]
Observation I.—Mr. C., age about twenty-eight, a man of scientific training and aptitudes. Shortly after his mother's death he repeatedly dreamed that she had come to life again. She had been buried, but it was somehow found out that she was not really dead. Mr. C. describes the painful intellectual struggles that went on in these dreams, the arguments in favour of death from the impossibility of prolonged life in the grave, and how these doubts were finally swallowed up in a sense of wonder and joy because his mother was actually there, alive, in his dream.
These dreams became less frequent as time went on, but some years later occurred an isolated dream which clearly shows a further stage in the same process. Mr. C. dreamed that his father had just returned home, and that he (the dreamer) was puzzled to make out where his mother was. After puzzling a long time he asked his sister, but at the very moment he asked it flashed upon him—more, he thinks, with a feeling of relief at the solution of a painful difficulty than with grief—that his mother was dead.
Observation II.—Mrs. F., age about thirty, highly intelligent but of somewhat emotional temperament. A week after the death of a lifelong friend to whom she was greatly attached, Mrs. F. dreamed for the first time of her friend, finding that she was alive, and then in the course of the dream discovering that she had been buried alive.
A second dream occurred on the following night. Mrs. F. imagined that she went to see her friend, whom she found in bed, and to whom she told the strange things that she had heard (i.e., that the friend was dead). Her friend then gave Mrs. F. a few things as souvenirs. But on leaving the room Mrs. F. was told that her friend was really dead, and had spoken to her after death.