A monograph on sleep and dream: their physiology and psychology

by Edward W. Cox

The popular notion is that reason is the slumbering faculty. We talk of reason as being the special attribute of Man. In fact there is no such faculty. There is a mental process we call reasoning; but it is performed by the joint action of various mental faculties. One presents the things to be reasoned upon; another compares them and presents their resemblances and differences; a third enables us, by the process we call reasoning, to apply these resemblances and differences to some third subject and thus from the known to predicate the unknown.

It is familiar to every reader that this process of reasoning is not always suspended in dream. On the contrary, it is sometimes abnormally active. We reason rightly often, but on wrong premisses. What we are unable to discover in dream is the unreality of the subject matter upon which we are reasoning.

If, for instance, you dream that you are making a speech or preaching a sermon. In your dream you pursue a logical argument, but you found it upon imagined facts that are untrue and improbable, which the waking mind would not entertain for a moment, but which in your dream you accept as true and implicitly believe to be real.

We shall, perhaps, arrive at the solution of this problem by the process of exhaustion.

The faculty of imagination, that shapes to the dream ideal pictures of things, is not sleeping. The faculties that perform the process of reasoning are not sleeping. Comparison—the power to compare the ideal with the real—alone is wanting. We mistake the shadows of the mind for substances. We accept the brain-born visions as realities. Why? Because we are unable to compare them. In brief, Comparison is the faculty, paralysed in sleep, whose absence causes the credulity of dream.

Of this fact there can be no doubt. But a very formidable difficulty here presents itself. How and why is it that this faculty alone is found to slumber when the greater part of the mental mechanism is awake and active?

It has been one of the most perplexing problems of Psychology. A solution of it has occurred to me which I submit to the consideration of the reader, but as a suggestion merely. It is too novel to be offered as anything more than a suggestion.

Each mental faculty can perform only one act at the same instant of time. It is one of the conditions of existence here that all consciousness shall be in succession. Hence indeed our conception of time. If any other being could obtain many perceptions simultaneously, and not in succession, to that being there would be no time, in our sense of the term. But the process of comparison involves the contemplation together of the two things (or ideas of things) to be compared. This difficulty is removed by the double brain. Each brain presents one of the ideas to be compared and upon these the faculty of comparison employs itself, discerning their resemblances and differences. If so it be, the cause of our incapacity to discover the absurdities of dream is the partial paralysis (or sleep) of one of the two mental faculties that present the ideas of objects and the consequent incapacity of the faculty of comparison to discharge its proper function of informing us what of our mental impressions are real and what illusory.

And this raises a curious question as to the relative functions and operations of the two brains. In profound slumber, when both brains are sleeping, there is no consciousness—time is annihilated to such a sleeper and awakening seems to follow immediately upon falling asleep, although in reality many hours may have passed. When the brain is sleeping but partially there is some consciousness of time in sleep and of the lapse of time upon awaking. Is such partial sleep the slumber of one brain only, and are these phenomena of dream due to the action of that one brain deprived of the correcting influence of the other brain? Does the faculty of comparison fail to show us that our mental impressions are subjective and not objective because it is not assisted by the normal action of the duplicate faculty of the other brain? Comparison is the foundation of the process of reasoning. It has been noticed that persons suffering from hemiplegia—that is, from disease of one brain only—often lose the power to compare and consequently the capacity for reasoning readily and correctly. May it not be that a similar condition is produced by temporary paralysis of the brain in sleep? As already stated, the power to reason is not absent in dream. We often reason elaborately and well, taking the ideal pictures as real incidents. We accept as objective facts what are merely mental impressions and thus build an argument on an incorrect assumption. The reasoning is right, but the basis of it is false. Question each mental faculty in turn and it will appear that but one is at fault in dream—namely, comparison. We are unable to discern the difference between the mental and the sensual impression—the self-created and the sense-borne idea—because we are incompetent to compare them and it is by comparison alone that we can distinguish the false from the true. I throw out this, as a suggestion merely, to Mental Philosophers and Psychologists.

Indeed, the fact that we have two perfect brains with every mental faculty in duplicate (as contended by Sir Henry Holland and now conclusively established by the experiments of Brown-Sequard and Professor Ferrier), has opened a new field to the Mental Philosopher and Psychologist. It must have the most intimate relationship, not to the phenomena of Sleep and Dream alone but to all the phenomena of Mind. In this great fact will doubtless be found the obvious solution of many problems hitherto insoluble. Foremost among those philosophical puzzles has been the instantaneous lapse of the Mind into insanity in dream, and the no less marvellous manner in which upon waking we pass almost as quickly out of that insane condition into sanity.