mind can gaze upon the scene with any portion of tranquillity and composure. This mistake of conception for sensation is also the best key to the phenomena observed in madness. A madman has the conception of all the pageantry of a court, and so may any man in his senses; the difference is, the one knows it to be only a creation of his mind, the other really believes he sees dukes, and marquises, and all the splendour of a real court. If he is not very far gone, he pays some attention to the objects of sense about him, and tells you that he is confined in this sorry situation by the perfidy and rebellion of his subjects. As the disease further advances, he totally neglects the objects of his senses; - does not see that he sleeps on straw and is chained down, but abandons himself wholly to the creations of his mind, and riots in every extravagance of thought. This, though by far the most common species of insanity, is not the only one. There are some persons quite rational in their perceptions, who are considered as deranged only from a morbid association of ideas; as in the instance of the patient mentioned in Mr. Haslam's book, who persevered in a vegetable diet because, he said, roast and boiled meat felt the most exquisite pain while any person was devouring them.

The mistaking of conceptions for sensations appears

also to be the proper explanation of what passes in our minds during sleep. To consider sleep aright, we must divide it into stages. In profound sleep, there is no evidence that we think at all. When we have been exhausted with great fatigue or acute pain, we often lie motionless for hours, without the smallest recollection that a single idea has past through our minds: the periods of sleeping and waking appear to be consecutive instants of time. In this state of sleep it seems as if every operation of the mind were entirely suspended; and in the instance of those who have taken quantities of opium, or become drowsy from long journeys over snow, it seems to have a great tendency to death. We frequently dream in our sleep without recollecting the slightest feature of our dreams when we awake. It would appear at first, that processes of thought which have made such faint impressions on the memory must have been the slightest and most disconnected of all dreams; and yet the most rational and systematic dreamers-those who walk in their sleep-have seldom or ever the most distant recollection that they have been dreaming at all.

In the common state of sleep, where we dream without stirring, or, at least, without walking about, there seems to be, first, a great diminution of the power of the will over the body, but by no means a total suspension of that power: for a person much agitated in his dreams can cry out, and therefore subject the organs of speech to his will; or he can toss about his hands and feet, and so subject those parts of his body to his will; but, however, the influence of the will upon the body, though not wholly suspended, is, certainly considerably weakened. In this sort of sleep it is still less suspended over the mind, for a man makes a bargain in his dreams, and examines the terms of the bargain, and dwells upon one part of it with some accuracy; he argues in his sleep, not merely repeating, as has been said, arguments

I

which have occurred to him in his waking hours, but inventing new ones, with some pains and attention. mention these circumstances in opposition to those who have contended that the influence of the will is entirely suspended in sleep. I should think diminished would be a better word,—for suspended it certainly is not in the body, and still less so in the mind; though its power is incomparably less than in our waking hours. But the most striking phenomenon in our sleep is that which I have shown to take place in madness- the confusion between our sensations and conceptions. I may think when I am awake of a chariot drawn by tigers; but I know then, it is merely a thought. When I am in a reverie, I am in a confused state between doubt and belief of its existence. When I am asleep, I take this thought for a reality; and as our sensations follow one another in a regular and established order, and our conceptions are very loosely connected together, this is the reason of all the absurdity and incongruity of our dreams. Indeed, sense and nonsense, congruity and incongruity, are only determined by the outer world; and we consider our conceptions to be wild or rational only as they correspond with it.

According as sleep is more or less perfect, sensations do or do not produce an effect upon the mind, exactly the same as in reverie or in madness. A person may, in some cases, sleep so soundly, that the firing a pistol close to his ear will not rouse him;-at other times the slightest sensation of light or noise will rouse him. A sort of intermediate state between these two is that where the sensation comes to the mind in so imperfect a state, that it produces some effect, upon the current of conceptions without correcting them. If there is a window left open, and the cold air blows in, the sufferer may think himself on the top of Mount Caucasus, buried in the snow; or the cat making a noise shall immediately transport him in imagination to the Opera.

The most singular phenomenon respecting sleep is somnambulism, or walking in the sleep. The instances are innumerable of men who have walked along the ridges of houses in their sleep; have got up, dressed themselves, taken pen, ink, and paper, have written very rationally and connectedly, and acted precisely as they would have done had they been awake. Out of this mass of histories I shall make a short extract from a well-authenticated one, reported by a Physical Society at Lausanne. It is the case of Devaux, a lad about thirteen years of age, who lived in the town of Vevay. He did not walk in his sleep every night, but passed sometimes six or seven weeks without a fit of somnambulism. Before the fit begins he utters broken words, sits up in his bed, abruptly begins to talk with more coherence, then rises, and goes wherever the nature of his dream prompts him. Having risen one night with the intention of eating grapes, he left the house, went through the town, and passed on to a vineyard, where he expected good cheer. He was followed by several persons, who kept at a distance from him, one of whom fired a pistol, the noise of which immediately awoke him, and he fell down in a fit. Once he was observed dressing himself in the dark. His clothes were on a large table mixed with those of some other persons. At last a light was brought: he separated the clothes and dressed himself with sufficient precision. Another time he got out of bed and finished a piece of writing, in order, as he said, to please his master. It consisted of three kinds of writing, text, half-text, and small writing, each of them performed with the proper pen. He drew, in the corner of the same paper, the figure of a hat. He then asked for a penknife, to take out a blot of ink which he had made between two letters; and he erased it without injuring either. Lastly, he made some calculations with great accuracy.

Now in this case of Devaux's, and in all such cases

of somnambulism, there is an approach to the awaking state of the mind: they afford an intermediate step between sleep and vigilance, and differ only from madness in the time of their duration. For in somnambulism the will has recovered great part of its dominion over the body and mind which it had lost in perfect sleep; for we see that a somnambulist walks about, and thinks, and reasons, and acts, with a great share of precision. The difference between a somnambulist and a man awake is, that the first distinguishes between his sensations and perceptions only in part, the latter entirely. Devaux got up and wrote a copy for his master, -he saw the pen and ink, and the writing, and various other things, as plainly as if he had been awake; but he did not attend to the appearance of the room, the beds, and the faces about him; he most probably thought he was in school, with his school-fellows about him, and so far he was under the influence of his conceptions. This is just the case with innumerable madmen we see in Bedlam. Somnambulism continued would, so far as I can see, differ nothing from madness. Dreaming differs from madness only in the diminution of the power of the will; excepting that there are very few madmen in Bedlam so mad as a dreamer. There seems also to be a certain connection between the augmented power of conception and the diminished power of will; so that a man becomes, in sleeping, motionless, exactly as he becomes mad, and regains his power of moving as he regains his power of moving for a rational purpose. This happens, luckily enough for dreamers, who would otherwise infallibly break their limbs every time they dreamt ; and for the somnambulist, who, when he can move about, has acquired a considerable share of reason: so that we may perceive, if these observations be true, the following phenomena to take place, exactly in proportion as the outward senses lose their power, and the conceptions acquire a greater vigour than is natural to them: