non difficulty in getting his mental powers into their continued very long. By lying flat upon a millstone usual state of activity. Opium, hyoscyamus, aconite, belladonna, and the whole tribe of narcotics, induce sleep, partly by a specific power which they exert on the nerves of the stomach, and partly by inducing an apoplectic state of the brain. The former effect is occasioned by a moderate-the latter by an over dose. while performing its evolutions, sleep is soon produced, A heated church and a dull sermon are almost sure and death, without pain, would be the result, if the exto provoke sleep. There are few men whose powers periment were greatly protracted. Apoplexy, which are equal to the task of opposing the joint operation of consists of a turgid state of the cerebral vessels, protwo such potent influences. They act on the spirit duces perhaps the most complete sleep that is known, like narcotics, and the person seems as if involved in a in so far that, while it continues it is utterly impossicloud of anconite or belladonna. The heat of the church ble to waken the individual: no stimulus, however might be resisted, but the sermon is irresistable. Its powerful, has any influence in arousing his dormant famonotony falls in leaden accents upon the ear, and soon culties. When the circulating mass in the brain is subdues the most powerful attention. Variety, whether diminished beyond a certain extent, it has the same of sight or sound, prevents sleep, while monotony of effect on the opposite state; whence excessive loss of all kinds is apt to induce it. The murmuring of a blood excites sleep. river, the sound of a Eolian harp, the echo of a distant cascade, the ticking of a clock, the hum of becs under a burning sun, and the pealing of a remote hell, all exercise the same influence. So conscious was Boerhaave of the power of monotony, that in order to procure sleep for a patient, he directed water to be placed in such a situation as to drop continually on a brass pan. When there is no excitement, sleep is sure to follow. We are all kept awake by some mental or bodily stimulus, and when that is removed our wakefulness is at an end. Want of stimulus, especially in a heated atmosphere, produces powerful effects; but where sufficient stimulus exists, we overcome the effects of the heat, and keep awake in spite of it. Thus, in a crowded church, where a dull, inanimate preacher would throw the congregation into a deep slumber, such a man as Massilon, or Chalmers, would keep them in a state of keen excitement. He would arrest their attention, and counteract whatever tendency to sleep would otherwise have existed. In like manner, a prosing, monotonous, long-winded acquaintance apt to make us doze, while another of a lively, energetic conversation keeps us brisk and awake. It will generally be found that the reasoning faculties are those which are soonest prostrated by slumber, and the imaginative the least so. A person would more readily fall asleep if listening to a profound piece of argumentation, than to a humorous or fanciful story; and probably more have slumbered over the pages of Bacon and Locke, than over those of Shakspeare and Milton. Cold produces sleep as well as heat, but to do so a very low temperature is necessary, particularly with regard to the human race; for, when cold is not excessive, it prevents, instead of occasioning slumber: in illustration of which, I may mention the case of several unfortunate women, who lived thirty-four days in a small room overwhelmed with the snow, and who scarcely slept during the whole of that period. In very northern and southern latitudes, persons often lose their Lives by lying down in a state of drowsiness, occasioned by intense cold. The winter sleep, or hybernation of animals, arises from cold; but as this species of slumber is of a very peculiar description; I have discussed it separately in another part of the work. The finished gratification of all ardent desires has the effect of inducing slumber; hence, after any keen excitement, the mind becomes exhausted, and speedily relapses into this state. Attention to a single sensation has the same effect. This has been exemplified in the case of all kinds of monotony, where there is a want of variety to stimulate the ideas, and keep them on the alert. If the mind,' says Cullen, 'is attached to a single sensation, it is brought very nearly to the state of the total absence of impression; or, in other words, to the state most closely bordering upon sleep. Remove those stimuli which keep it employed, and sleep ensues at any time. Any thing which mechanically determines the blood to the brain, acts in a similar manner, such as whirling round for a great length of time, ascending a lofty mountain, or swinging to and fro. The first and last of these actions give rise to much giddiness, followed by intense slumber, and at last by death, if they be A heavy meal, especially if the stomach is at the same time weak, is apt to induce sleep. In ordinary circumstances, the nervous energy or sensorial power of this viscus is sufficient to carry on its functions; but when an excess of food is thrown upon it, it is then unable to furnish, from its own resources, the powers requisite for digestion. In such a case it draws upon the whole body-upon the chest, the limbs, &c., from whence it is supplied with the sensorial power of which it is deficient; and is thus enabled to perform that which by its own unassisted means it never could have accomplished. But mark the consequences of such accommodation! Those parts, by communicating vigor to the stomach, become themselves debilitated in a corresponding ratio, and get into a state analogous to that from which they had extricated this Viscus. The extremities become cold, the respiration heavy and stertorous, and the brain torpid. In consequence of the torpor of the brain, sleep ensues. had parted with that portion of sensorial energy which kept it awake, and by supplying another organ is itself thrown into the state of sleep. It is a curious fact, that the feeling of sleep is most strong while the food remains on the stomach, shortly after the accession of the digestive process, and before that operation which converts the nourishment into chyle has taken place. When, therefore, the sensorial power is sufficiently exhausted, we naturally fall asleep. As this exhaustion, however, is a gradual process, so is that of slumber. Previous to its accession, a feeling of universal lassitude prevails, and exhibits itself in yawning,* peevishness, heaviness, and weakness of the eyes; indifference to surrounding objects, and all the characteristics of fatigue. If the person be seated, his head nods and droops; the muscles become relaxed; and, when circumstances admit of it, the limbs are thrown into the recumbent position, or that most favorable for complete inaction. The senses then become unconscious of impressions, and, one after the other, part with sensation; the sight first, then taste, smell, hearing, and touch, all in regular order. The brain does not all at once glide into repose: its different organs being successively thrown into this state; one dropping asleep, then another, then a third, till the whole are locked up in the fetters of slumber. This gradual process of intellectual obliteration is a sort of confused dream-a mild delirium which always precedes sleep. The ideas have no resting-place, but float about in the con *We yawn before falling asleep and when we wake; yawn ing, therefore, precedes and follows sleep. It seems an effort of nature to restore the just equilibrium between the flexor and ex. tensor muscles. The former have a natural predominancy in the system; and on their being fatigued, we, by an effort of the will, or rather by a species of instinct, put the latter into action for the purpose of redressing the balance, and poising the respective muscular powers. We do the same thing on awaking, or even on getting up from a recumbent posture-the flexors in such cir cumstances having prevailed over the extensors, which were in a great measure inert. fused tabernacle of the mind, giving rise to images of the most perplexing description. In this state they continue for some time, until, as sleep becomes more profound, the brain is left to thorough repose, and they disappear altogether. Sleep produces other important changes in the system. The rapidity of the circulation is diminished, and, as a natural consequence, that of respiration: the force of neither function, however, is impaired; but, on the contrary, rather increased. Vascular action is diminished in the brain and organs of volition, while digestion and absorption shall proceed with increased energy. The truth of most of these propositions it is not difficult to establish. The diminished quickness of the circulation is shown in the pulse, which slower and fuller than in the waking state; that of respiration in the more deliberate breathing which accompanies sleep. Diminished action of the brain is evident from the abolition of its functions, as well as direct evidence. A case is related by Blumenbach, of a person who had been trepanned, and whose brain was observed to sink when he was asleep, and swell out when he was awake. As for the lessened vascular action in the voluntary powers, this is rendered obvious by the lower temperature on the surface which takes place during the slumbering state. Moreover, in low typhus, cynanche maligna, and other affections attended with a putrid diathesis, the petechiae usually appear during sleep when the general circulation is least vigorous, while the paroxysms of reaction or delirium take place, for the most part, in the morning when it is in greater strength and activity. In some individuals the stronger and more laborious respiration of sleep is made manifest by that stertorous sound commonly denominated snoring. Stout apoplectic people those who snuff much or sleep with their mouths open, are most given to this habit. It seems to arise principally from the force with which the air is drawn into the lungs in sleep. The respiratory muscles being less easily excited during this state do not act so readily, and the air is consequently admitted into the chest with some degree of effort. This, combined with the relaxed state of the fauces, gives rise to the stertorous noise. Snuffing, by obstructing the nasal passages and thus rendering breathing more difficult, has the same effect; consequently snuffers are very often great snorers. The less rapidly the blood is propelled through the lungs, the slower is the respiration, and the louder the stertor becomes. Apoplexy, by impairing the sensibility of the respiratory organs, and thus reducing the frequency of breathing, produces snoring to a great extent; and all cerebral congestions have, to a greater or less degree, the same effect. That sleep increases absorption is shown in the disappearance or diminution of many swellings, especially cedema of the extremities, which often disappears in the night and recurs in the daytime, even when the patient keeps his bed, a proof that its disappearance does not not always depend on the position of the body: that it increases digestion, and, as a natural consequence, nutrition, is rendered probable by many circumstances: hence it is the period in which the regeneration of the body chiefly takes place. Were there even no augmentation given to the assimilative function, as is maintained by Broussais and some other physiologists, it is clear that the body would be more thoroughly nourished than when awake, for all those actions which exhaust it in the latter condition are quiescent, and it remains in a state of rest, silently accumulating power, without expending any. Sleep lessens all the secretions, with one exceptionthat of the skin. The urinary, salivary, and bronchial discharges, the secretions from the nose, eyes, and ears, are all formed less copiously than in the waking state. The same rule holds with regard to other secretions hence diarrhea, menorrhagia, &c., are checked during the intervals of slumber. From the diminished vascular action going on upon the surface, we would be apt to expect a decrease of perspiration, but the reverse is the case. Sleep relaxes the cutaneous vessels, and they secrete more copiously than in the waking state. According to Sanctorius, a person sleeping some hours undisturbed, will perspire insensibly twice as much as one awake. This tendency of sleep to produce perspiration is strikingly exhibited in diseases of debility; whence the nocturnal sweats so prevailing and so destructive in all cachectic affections. Sanctorius farther states, that the insensible perspiration is not only more abundant, but less acrimonious during sleep than in the waking state; that, if diminished during the day, the succeeding sleep is disturbed and broken, and that the diminution in consequence of too short a sleep, disposes to fever, unless the equilibrium is established, on the following day, by a more copious perspiration. Sleep produces peculiar effects upon the organs of vision. A priori, we might expect that, during this state, the pupil would be largely dilated in consequence of the light being shut out. On opening the eyelids cautionsly it is seen to be contracted; it then quivers with an irregular motion, as if disposed to dilate, but at length ceases to move, and remains in a contracted state till the person awakes. This fact I have often verified by inspecting the eyes of children. Sleep also communicates to these organs a great accession of sensibility, so much so, that they are extremely dazzled by a clear light. This, it is true, happens on coming out of a dark into a light room, or opening our eyes upon the sunshine even when we are awake, but the effect is much stronger when we have previously been in deep slumber. Sleep may be natural or diseased-the former arising from such causes as exhaust the sensorial power, such as fatigue, pain, or protracted anxiety of mind; the latter from cerebral congestion, such as apoplexy or plethora. The great distinction between these varieties is, that the one can be broken by moderate stimuli, while the other requires either excessive stimuli, or the removal of the particular cause which gave rise to it During complete sleep no sensation whatever is experienced by the individual: he neither feels pain, hunger, thirst, nor the ordinary desires of nature. He may be awakened to a sense of such feelings, but during perexistence-if they can indeed be said to exist where fect repose he has no consciousness whatever of their they are not felt. For the same reason, we may touch him without his feeling it; neither is he sensible to sounds, to light, or to odours. When, however, the slumber is not very profound, he may hear music or conversation, and have a sense of pain, hunger, and thirst; and, although not awakened by such circumpressions, caught by the senses, often give rise to the stances, may recollect them afterwards. These immost extraordinary mental combinations, and form the groundwork of the most elaborate dreams. I am of opinion that we rarely pass the whole of any one night in a state of perfect slumber. My reason for this supposition is, that we very seldom remain during the whole of that period in the position in which we fall asleep. This change of posture must have been occasioned by some emotion, however obscure, affecting the mind, and through it the organs of volition, whereas in complete sleep we experience no emotion whatever. The position usually assumed in sleep has been mentioned; but sleep may ensue in any posture of the body; persons fall asleep on horseback, and continue riding in this state for a long time without been awakened. Horses sometimes sleep for hours in the standing posture; and the circumstance of somnamba PHILOSOPHY OF SLEEP. lism shows that the same thing may occur in the hu man race. Some animals, such as the hare, sleep with their eyes open; and I have known similar instances in the human subject. But the organ is dead to the ordinary stimulus of light, and sees no more than if completely shut. Animals which prey by night, such as the cat, hyena, &c., pass the greater part of their time in sleep; while those that do not, continue longer awake than asleep. The latter slumber part of the night and continue awake so long as the sun continues above the horizon. the day time The propensity of the former to sleep seems to proceed from the structure of their eyes; as they see much better in darkness than in light, and consequently pass in slumber that period in which their vision is of least avail to them. It is a very curious fact, however, that these animals, when kept in captivity, reverse the order of their nature, and remain awake by day while they sleep by night. This fact has been ascertained in the menagerie at Paris. In such cases I apprehend that some corresponding change must take place in the structure of the eyes, assimilating them to those animals which naturally sleep by night. | tain hour, the anxiety of mind thus produced not only Discase exercises a powerful influence upon sleep. All affections attended with acute pain prevent it, in consequence of the undue accumulation which they occasion of sensorial power. This is especially the case where there is much active determination of blood to the head, as in phrenetic affections, and fevers in general. Sleep is always much disturbed in hydrothorax; and almost every disease affects it, more or less; some preventing it altogether, some limiting the natural proportion, some inducing fearful dreams, and all acting with a power proportioned to the direct or indirect influence which they exercise upon the sensorium. From the increased irratibility of the frame and relaxed state of the cutaneous vessels during sleep, the system at that time is peculiarly apt to be acted upon by all impressions, especially of cold; and those who fall asleep exposed to a current of air are far more apt to feel the consequences thereof than if they were broad awake. By a law of nature the sensibility of the system is increased by any suspension of the mental or voluntary powers, for the same reason that it is diminished, while these powers resume their action. In drunkenness, for instance, where the mind is vehementexcited, we are far less susceptible of cold than in a state of sobriety. M. Castel observes, that the greater part of animals It is precisely sleep longer in winter than in summer. on account of perspiration that in the first of these seasons sleep is more necessary than in the second. In winter, the want of perspiration during the day is furnished in sleep; in summer, the diurnal sweat supplies that of the night, and renders much sleep less necessary. In other words, during summer the perspiration is so much excited by atmospheric temperature, that a shorter time is sufficient to give issue to the fluids For the which have to be expelled by this means. same reason, the inhabitants of very cold climates sleep more than those who live in the warmer latitudes. The profoundness of sleep differs greatly in different individuals. The repose of some is extremely deep; One will scarcely that of others quite the reverse. obey the roar of cannon; another will start at the chirping of a cricket or the faintest dazzling of the moonbeams. Heavy-minded, phlegmatic people generally belong to the former class; the irritable, the ner-ly vous, and the hypochondriac to the latter, although we shall at times find the cases reversed with regard to the nature of sleep enjoyed by these different temperaments. Man is almost the only animal in whom much The lower variety is to be found in this respect. grades are distinguished by a certain character, so far as their slumber is concerned, and this character runs through the whole race; thus, all hares, cats, &c., are light sleepers; all bears, turtles, badgers, &c., are the In man, the varieties are infinite. Much of this depends upon the age and temperament of the individual, and much upon custom. reverse. The profoundness of sleep differs also during the same night. For the first four or five hours, the slumber is much heavier than towards morning. The cause of such difference is obvious; for we go to bed exhausted by previous fatigue, and consequently enjoy sound repose, but, in the course of a few hours, the necessity for this gradually abates, and the slumber naturally becomes lighter. That sleep from which, we are easily roused is the healthiest very profound slumber partakes of the nature of apoplexy. On being suddenly awakened from a profound sleep When there is a necessity for our getting up at a cer- Sleep is much modified by habit. Thus, an old artil- a miller being very ill, his mill was stopped that he sation which, by breaking the monotony, became so, and caused the sleeper to awake. The effects of habit may be illustrated in various ways. If a person, for instance, is accustomed to go to rest exactly at nine o'clock in the evening, and to rise again at six in the morning, though the time of going to sleep be occasionally protracted till twelve, he will yet awake at his usual hour of six; or, if his sleep be continued by darkness, quietude or other causes, till the day be farther advanced, the desire for sleep will return in the evening at nine.' Persons who are much in the habit of having their repose broken, seldom sleep either long or profoundly, however much they may be left undisturbed. This is shown in the cases of soldiers and seamen, nurses, mothers, and keepers. life; but very young children always sleep away the most of their time. At this early period, the nerves being extremely sensitive and unaccustomed to impressions, become easily fatigued. As the children get older, the brain besides becoming habituated to impressions, acquires an accession of sensorial power, which tends to keep it longer awake. For the first two or three years, children sleep more than once in the twenty-four hours. The state of the foetus has been denominated, by some writers, a continued sleep, but the propriety of this definition may be doubted; for the mind having never yet manifested itself, and the voluntary organs never having been exercised, can hardly be said to exist in slumber, a condition which supposes a previous waking state of the functions. Middle-aged persons who lead an active life, seldom sleep above eight or nine hours in the twenty-four, however much longer they may lie in bed; while a rich, lazy, and gormandizing citizen will sleep twelve or thirteen hours at a time. Seamen and soldiers on duty can, from habit, sleep when they will, and wake when they will. The Emperor Napoleon was a striking instance of this fact. Captain Barclay, when performing his extraordinary feat in walking a mile an hour for a thousand succes- Sleep is greatly modified in old people. They usualsive hours, obtained at last such a mastery over him-ly slumber little, and not at all profoundly. Sometimes, self, that he fell asleep the instant he lay down. however, when they get into a state of dotage, in conSome persons cannot sleep from home, or on a different sequence of extreme old age, the phenomena of childbed from their usual one some cannot sleep on a hard, hood once more appear, and they pass the greater part others on a soft bed. A low pillow prevents sleep in of their time in sleep. The repose of the aged is most some, a high one in others. The faculty of remaining apt to take place immediately after taking food, while asleep for a great length of time, is possessed by some they often solicit it in vain at that period at which, durindividuals. Such was the case with Quin, the cele-ing the former years of their lives, they had been accusbrated player, who could slumber for twenty-four hours successively with Elizabeth Orvin, who spent threefourths of her life in sleep-with Elizabeth Perkins, who slept for a week or a fortnight at a time-with Mary Lyall, who did the same for six successive weeksand with many others, more or less remarkable. In Bowyer's life of Beattie, a curious anecdote is related of Dr Reid, viz., that he could take as much food and immediately afterwards as much sleep as were sufficient for two days. tomed to enjoy it. The celebrated de Moivre slept twenty hours out of the twenty-four, and Thomas Parr latterly slept away by far the greater part of his exist ence. Those who eat heartily, and have strong digestive powers, usually sleep much. The great portion of sleep required by infants is owing, in part, to the prodigious activity of their digestive powers. The majority of animals sleep after eating, and man has a strong tendency to do the same thing, especially when oppressed with heat. In the summer season, a strong inclination is often felt, to sleep after dinner, when the weather is very warm. Á heavy meal, which produces no uneasy feeling while the person, will often do so if he fall asleep. According to Dr. Darwin, this proceeds from the sensorial actions being increased, when the volition is suspended. The digestion from this circumstance goes on with increased rapidity. Heat is produced in the system faster than it is expended; and, operating on the sensitive actions, carries them beyond the limitations of pleasure, producing, as is common in such cases, increased frequency of pulse.' In this case, incomplete sleep is supposed, for, when the slumber is perfect, no sensation whatever, either painful or the reverse, can be experienced. A phenomenon of an opposite character is also sometimes observed, for there are individuals who can subsist upon a surprisingly small portion of sleep. The celebrated General Elliot was an instance of this kind : he never slept more than four hours out of the twentyfour. In all other respects he was strikingly abstinent; his food consisting wholly of bread, water, and vegetables. In a letter communicated to Sir John Sinclair, by John Gordon, Esq. of Swiney, Caithness, mention is made of a person named James Mackay, of Skerray, who died in Strathnaver in the year 1797, aged ninety-one he only slept, on an average, four hours in the twenty-four, and was a remarkably robust and healthy man. Frederick the Great, of Prussia, and the illustrious surgeon, John Hunter, only slept five hours in the same period; and the sleep of the active-minded is always much less than that of the listless and indolent. The celebrated French General Pichcgru, informed Sir Gilbert Blane, that, during a whole year's campaigns, he had not above one hour's sleep in the twenty-four. I know a lady who never sleeps above half an hour at a time, and the whole period of whose sleep does not exceed three or four hours in the twenty-four; and yet she is in the enjoyment of excellent health. Gooch gives an instance of a man who slept only for fifteen minutes out of the twenty-four hours, and even this was only a kind of dozing, and not a perfect sleep: notwithstanding which, he enjoyed good health, and reached his seventy-third year. I strongly suspect there must be some mistake in this case, for it is not conceivable that human nature could subsist upon such a limited portion of repose. Instances have been related of persons who never slept; but these must be regarded as purely fabu-begin to act one after the other; the senses do the lous. The period of life modifies sleep materially. When a man is about his grand climateric, or a few years beyond it, he slumbers less than at any former period of In recovering from long protracted illness, accompsnied with great want of rest, we generally sleep muchfar more, indeed, than during the most perfect health. This seems to be a provision of nature for restoring the vigour which had been lost during disease, and bringing back the body to its former state. So completely does this appear to be the case, that as soon as a tho rough restoration to health takes place, the portion of sleep diminishes till it is brought to the standard at which it originally stood before the accession of illness. After continuing a certain time asleep, we awake, stretch ourselves, open our eyes, rub them, and yawn several times. At the moment of awaking, there is some confusion of ideas, but this immediately wears away. The mental faculties from being in utter torpor, *In the gradual progress from intense sleep, when there can be no dream, to the moment of perfect vigilance, see what occurs. The first cerebral organ that awakes enters into the train of thinking connected with its faculty: some kind of dream is the result; as organ after organ awakes, the dream becomes more vivid; and as the number of active organs increases, so same. At last, the mind, the senses, and the locomotion being completely restored, what are our sensations? Instead of the listlessness, lassitude, and general fatigue experienced on lying down, we feel vigorous and refreshed. The body is stronger, the thoughts clearer and more composed; we think coolly, clearly, rationally, and can often comprehend with ease what baffled us on the previous night. One or two other points remain to be noticed. On awaking, the eyes are painfully affected by the light, but this shortly wears away, and we then feel them stronger than when we went to bed. The muscular power, also, for a few seconds, is affected. We totter when we get up; and if we lay hold of any thing, the hand lacks its wonted strength. This, however, as the current of nervous energy is restored throughout the e: muscles, immediately disappears; and we straightway possess redoubled vigour. On examining the urine, we find that it is higher in its colour than when we lay down. The saliva is more viscid, the phlegm harder and tougher, the eyes glutinous, and the nostrils dry. If we betake ourselves to the scale, we find that our weight has diminished in consequence of the nocturnal perspirations; while, by subjecting our stature to measurement, we shall see that we are taller by nearly an inch than on the preceding night. This fact was correctly ascertained in a great variety of instances, by Mr. Wasse, Rector of Aynho in Northumberland; and is sufficiently accounted for by the intervertebral cartilages recovering their elasticity, in consequence of the bodily weight being taken off them during the recumbent posture of sleep. Such are the leading phenomena of sleep. With regard to the purposes which it serves in the economy, these are too obvious to require much detail. Its main object is to restore the strength expended during wakefulness; to recruit the body by promoting nutrition and giving rest to the muscles; and to renovate the mind by the repose which it affords the brain. Action is necessarily followed by exhaustion; sleep by checking the one restrains the other, and keeps the animal machine in due vigour. Mr Carmichael supposes sleep to be the period when assimilation goes on in the brain. In this respect, I believe that the brain is not differently situated from the rest of the body. There, as elsewhere, the assimilative process proceeds both in the slumbering and in the waking state; but that it is only at work in the brain during sleep analogy forbids us to admit. So long as circulation continues, a deposition of matter is going on; and circulation, we all know, is at work in the brain as in other organs, whether we be asleep or awake. According to Richerand, one of the great purposes, served by sleep, is to diminish the activity of the circulation, which a state of wakefulness has the invariable effect of increasing. The exciting causes' be observes, to which organs are subject during the day, tend progressively to increase their acton. The throbbings of the heart, for instance, are more frequent at night than in the morning; and this action, gradually, accelerated, would soon be carried to such a degree of activity as to be inconsistent with life, if its velocity were not moderated at intervals by the recurrence of sleep.' Our 6 To detail the beneficent purposes served by sleep in the cure of diseases, as well as in health, would be a work of supererogation. They are felt and recognised by mankind as so indispensable to strength, to happiness, and to life itself, that he who dispenses with that portion of repose required by the wants of nature, is in reality curtailing the duration of its own existence. does the complication of dreams; and if all the internal organs are awake, the man is still asieën i i awakening senses Leing him into direct communi world.' Carmicha heim, p. 92. CHAPTER III. DREAMING. In perfect sleep, as we have elsewhere stated, there is a quiescence of all the organs which compose the brain; but when, in consequence of some inward excitement, one organ or more continues awake, while the remainder are in repose, a state of incomplete sleep is the result, and we have the phenomena of dreaming. If, for instance, any irritation, such as pain, fever, drunkenness, or a heavy meal, should throw the perceptive organs into a state of action while the reflecting ones continue asleep, we have a consciousness of objects, colors, or sounds being presented to us, just as if the former organs were actually stimulated by having such impressions communicated to them by the external senses;* while in consequence of the repose of the reflecting organs, we are unable to rectify the illusions, and conceive that the scenes passing before us, This want of mutual co-operation between the differor the sounds that we hear, have a real existence. ent organs of the brain accounts for the disjointed nature, the absurdities, and incoherencies of dreams. Many other doctrines have been started by philosophers, but I am not aware of any which can lay claim even to plausibility; some, indeed, are so chimerical, and so totally unsupported by evidence, that it is difficult to conceive how they ever entered into the imaginations of their founders. Baxter, for instance, in his Treatise on the Immortality of the Soul,' endeavours to show that dreams are produced by the agency of some spiritual beings, who either amuse, or employ imaginary transaction with which they are employed in themselves seriously, in engaging mankind in all those dreaming. The theory of Democritus and Lucretius is equally whimsical. They accounted for dreams by supposing that spectres, and simulacra of corporeal things constantly emitted from them, and floating up and down in the air, come and assault the soul in sleep. The most prevailing doctrine is that of the Cartesians, who supposed that the mind was continually active in sleep; in other words, that during this state we were always dreaming. Hazlitt, in his Round Table,' has taken the same view of the subject, and alleges, that if a person is awakened at any given time and asked what ed to a train of associations with which his mind has he has been dreaming about, he will at once be recallit is not sustained by facts; experiments made on purbeer, busied previously. Unfortunately for this theory pose having shown that, though in some few instances, is described, yet in the great majority he had no conthe individual had such a consciousness of dreaming as therefore, so far as direct evidence is concerned must sciousness of any thing of the kind. The doctrine, fall to the ground; and yet, unsupported as it is either by proof or analogy, this is the fashionable hypothesis of the schools, and the one most in vogue among our best metaphysical writers. sanity. Dr. Abercrombie defines the difference beThere is a strong analogy between dreaming and in tween the two states to be, that in the latter the erroneous impressiou, being permanent, affects the conduct; produced, because the vision is dissipated on awaking. whereas in dreaming, no influence on the conduct is in somnambulism and sleep-talking, the conduct is inThis definition is nearly, but not wholly correct; for fluenced by the prevailing dream. Dr. Rush has, with great shrewdness, remarked, that a dream may be considered as a transient paroxysm of delirium, and delirium as a permanent dream. Man is not the only animal subject to dreaming. We have every reason to believe that many of the lower * This internal stimulation of particular organs without the concurrence of outward impressions by the senses, is more fully stated under the head of Spectral Illusions. |