has been found in the morning thorough-and dreams is not entitled to repose on ly worked out. Verses Latin as well his own experience only. A dozen peras English are said to have been made sons would probably give as many differin the night, with no consciousness of the ent versions of their particular consciousfact till they came to the morning memory. ness in the matter; and it is not easy to Nevertheless, we must regard the evi- draw averages from these fleeting shaddence here as insufficient, seeing how ows of the night. They change with age, commonly such statements are careless and other conditions of life, moral and inor exaggerated; how broken and desul- tellectual, which govern sleep and the tory are the conditions and memories of dreams associated with it. The simple, the night; and how likely it is that the but touching lines, time just antecedent to waking" quum somnia vera"-may be that in which these curious feats are accomplished. The drowsiness of the evening is often as much an impediment to thought as the light sleep of the morning.*

Thou hast been called, O Sleep, the friend of
But 'tis the happy who have called thee so,

woe,

point at one familiar source of this diversity, but there are many others, of which we shall speak hereafter.

We must, then, relegate this matter to the limbo of questions admitting neither In prosecuting the subject, we must of proof or disproof. Like many others, first refer again to Sleep in its general in addition to its intrinsic difficulties, it is sense, as the function of life, destined to encumbered and perplexed by ambigui- the restoration of those vital powers which ties of language. The very term of con- are exhausted or impaired by the very act sciousness, so essential to the discussion, of living. Here we are on firmer ground. has hardly obtained a valid definition in Whatever anomalies may present themits relation to sleep and dreams -an am-selves, it is certain that sleep fulfils, and biguous one even in reference to our wak- is intended to fulfil, this great office of our nature. That which is taught us by ing state. Everything, indeed, that concerns personal identity- the Ego of the universal experience is amply confirmed different stages and states of our being and illustrated by physiological inquiry. has been under the dominion of unsettled The wonderful power, to which various terms in all ages of philosophy. Words names have been given, but which may have not inaptly been called "the count-best, and most simply, be described as ers of wise men, and the money of fools." nerve-force- an element acting through But even the wisest have been unwittingly the brain and nervous system in all the governed by them in questions thus ob

scure or insoluble.

phenomena of sensation, of motions voluntary and reflex, and of every function essential to animal life-is now so far

subjected to research, that even the velocity of its transmission through the nerves of sensation and voluntary motion

has

-a mat

been approximately ascertained. This eminent discovery, and the subtle methods by which it was accomplished, warrant the hope that further research may accomplish a similar numerical expression for the amount or quantity of the nerve-force at any given time ter bearing still more directly on the subject before us. If, indeed, this were attained, it would be only formulating in figures a fact of the reality of which we are well assured. We know that the force in question, thus acting through the total nervous system of the body, is the product (secrétion we may venture to call it)

* If adopting this term of "unconscious cerebration," we might fairly apply it to various familiar acts of the waking state. For example: we try to recollect a name or word, fail to do so, and abandon the attempt. Soon afterwards, without intermediate consciousness or effort, the name in question rushes upon the memory, as if by a sudden inspiration. What has here been the intervening cerebral process? In auding to this common vagary of memory, we of a peculiar organized tissue; - that it may notice another closely connected with it. A word is forgotten, and sought for in vain. But its initial letter, or some vague image of the word, hangs upon the mind, often furnishing a clue to its recovery. Such instances, trifling though they seem, serve well to illustrate the curious mechanism of this great faculty of our

nature.

varies in amount in different individuals, and in the same individual at different times that it is exhausted, more or less, by the vital actions, bodily and mental, to which it ministers and that it can

only be restored by food and sleep, each |ily organs, and requires the same interseverally needed for the process of re- mittent periods of repose and repair. pair. This manner of viewing the nerve- If other proof were needed of the great power, or force, as an element to be esti-function which sleep fulfils in the econmated by quantity by excess as well as deficiency we believe to be not only just in itself, but denoting a principle of singular value in every part of physiology, and through physiology, in pathology and the treatment of disease. Mr. Herbert Spencer, in commenting on this subject with his wonted ability, thus expresses the main facts, in which all other writers on Sleep more or less concur: —

Between this state (of sleep) and the waking state, the essential distinction is a great reduction of waste. The rate of waste falls so low, that the rate of repair exceeds it. It is not that during the period of activity waste goes on without repair, while during the period of inactivity repair goes on without waste, for the two always go on together. Very possibly probably even repair is as rapid during the day as during the night. But during the day the loss is greater than the gain; whereas during the night the gain is diminished by scarcely any loss. Hence results accumulation. There is a restoration of the nerve-tissue to its state of integrity.

omy of life, it may at once be found in the effects which follow the privation of this repair. A single sleepless night tells its tale, even to the most careless observer. A long series of such nights, resulting, as often happens, from an over-taxed and anxious brain, may often warrant serious apprehension, as an index of mischief already existing, or the cause of evil at hand. Instances of this kind, we believe, are familiar to the experience of every physician.

But here, as in so many other cases, the evil of deficiency has its counterpart in the evil of excess. Sleep protracted beyond the need of repair, and encroaching habitually upon the hours of waking action, impairs more or less the functions of the brain, and with them all the vital powers. This observation is as old as the days of Hippocrates and Aretæus, who severally and strongly comment upon it. The sleep of infancy, however, and that of old age, do not come under this category of excess. These are natural conditions, appertaining to the respective periods of life, and to be dealt with as such. In illness, morever, all ordinary rule and measure of sleep must be put aside. Distin

cases in which it is not an unequivocal good; and even in comatose state the brain, we believe, gains more from repose than from any artificial attempts to rouse it into action.

Here, then, is a force, an agent, whether we call it material or not, generated within the body, necessary in its nature to all the functions of the body, but ex-guishing it from Coma, there are very few hausted in maintaining them, and requiring periods of rest for its reproduction in adequate amount. When calling sleep "Nature's kind restorer," we use a poetical phrase, but express a physical fact. It is the restorer of that which is expend- There is another point to which we ed and lost. Its intermittent periods, its must here advert, in connexion with sleep duration and degree, and even many of as a function of repair. This is the fact what seem its anomalies, have all refer- familiarly known, that the portion of life ence, more or less direct, to this great so destined, is not limited to Man alone, function of repair-a function fulfilled, but goes far down in the scale of animal it may be, simply by suspension or mod- creation-possibly, or probably, in one ification of those actions which exhaust form or other, to the lowest grade and the nervous power, while reproduction of condition of animal life. The sleep even this force is going on-or possibly by changes in the brain itself, an effect of the conditions to which it is submitted in sleep.

of plants has become a phrase, not merely of poetic fancy, but of scientific appropriation. The curious facts regarding the hybernation of certain animals, though For it must be remembered that sleep they have kindred with the phenomena repairs not the vital functions only, but and even theory of ordinary sleep, yet simultaneously those functions which we present anomalies which associate them distinctively describe as mental attri- in some way with the vegetable world. butes, and of which the brain is, to our But the circumstance of greatest interest present limited comprehension, the or- in this matter is the capacity for dreamganic instrument. The intellectual part ing, so clearly and curiously attested in of our nature, taking the phrase in its those animals which come nearest to Man largest sense, is exhausted by its contin- in the scale of being. How far that conued exercise, in like manner as the bod-'dition which can rightly be defined as

dreaming descends in the scale, it would be impossible to say. Probably there is a gradation downwards in the same ratio as the sensorial faculties, and vanishing with them. The fact of dreaming in the higher animals is most familiar to us in the Dog-that noble creature - ad hominum commoditates generatus, as Cicero says of him—at once a companion and solace to man, and a subject for profound thought to all who care to reflect on the great problem of our relations to the inferior animal creation. The admission of the fact does not, however, carry us beyond the presumption that the dreams of other animals are a vague copy of the sensations and acts of their waking lives; with little of the intellectual part-if such it may be called of the human dream. "To urge in dreams the forest chase is the happy phrase of a poet, than whom no one better knew, or better loved, the Dog. And nothing is more likely than the fact here presumed. But seeing the difficulty of rightly remembering and expounding human dreams, there can be little chance of penetrating the mystery as presented to us in another and lower scale of being.

Thus far we have been speaking of the general characters of Sleep as a function of life. In what follows we shall seek, upon our own observation and that of others, to describe the phenomena more in detail; associating them with those of Dreams, from which, as we have seen, they can hardly be separated, even should there be certain conditions of sleep wholly free from this kindred.

avail ourselves of a short passage from one of these chapters in illustration of our meaning :

Sleep, then, in the most general and correct sense of the term, must be regarded not as one single state, but a succession of states in constant variation;- this variation consisting, not only in the different degrees in which the same sense or faculty is submitted to it; but also in the different proportions in which these several powers are under its influence at the same time. We thus associate together under a common principle all the phenomena, however remote and anomalous they may seem;- - from the bodily acts of the somnambulist; the vivid but inconsequent trains of thought excited by external impression; the occasional acute exercise of the intellect; and the energy of emotion-to that profound sleep, in which no impressions are received from the senses, no volition is exercised, and no consciousness or memory is left on waking, of the thoughts and feelings which have existed in the mind.

To this we may add, that such mode of regarding sleep brings its phenomena into closer relation with those of our waking existence, making them serve to mutual illustration, and to the solution of many anomalies which depend on this relation, and the manner in which the two states graduate into each other. It is impossible, indeed, for anyone, at all observant of the facts, to regard sleep as a single or simple function. We know that through the nervous system and circulation of the blood, all parts of the body, and more especially the organs of sense, are affected and altered by it. But these changes of state are ever varying in the same organ, as well as in the different organs of our complex frame; and The first step we have to make here is the inter-relations thus produced, were one essential to any successful prosecu- they more accessible to observation, tion of the inquiry. It is based on the would give us deepest insight into this clear recognition of the fact, that sleep, mysterious part of our nature. Every thus associated, is not one state merely, organ may be said to have a sleep of its but a multiplicity and continuous succes-own. The several senses, the voluntary sion of states; varying at every moment power, the functions of the brain in their in kind or degree; graduating from the totality, are not merely affected in differfirst yawn of drowsiness to the most pro-ent degrees at different times, but are found sleep, and undergoing similar differently affected in degree at the changes in the transition from this to the same time. These facts are now state of perfect wakefulness. Even thus generally recognized by physiologists. simply stated, it will be seen how com- Bichat (a man of original genius, premapletely this fact governs and gives guid- turely lost to science) thus tersely exance to the whole inquiry, rendering its presses them :-"Le sommeil général conditions, indeed, more complex, but af- est l'ensemble des sommeils particuliers." fording a clew to many collateral phe- M. Maury, though less explicit in his nomena otherwise wholly inexplicable. statement of it, manifestly adopts the Sir H. Holland, who has two chapters on same view, which, in truth, affords the Sleep and Dreams in his volume of only just definition of sleep, and its con"Mental Physiology," strongly advocates comitant phenomena. It is the view, this mode of treating the subject. We moreover, which most clearly expounds

the relation of these phenomena to the hours, or the consciousness of the sleeper, acts and changes of the waking state -a there is much real difference in its deconnexion which, however perplexed to gree in relation to the great function of our reason by the question of personal repair. A certain quantity of work is to consciousness, will be found more inti- be done, but it is done at very different mate the closer we look into it. As in rates. This diversity occurs in different the series of waking thoughts, sudden persons, and in the same person at difchanges are often made by impressions ferent times. One hour in one case may from without, so, as regards sleep and comprise as much of what is true sleep, dreams, we may presume that the as two or many hours in another; and breaches which occur in their continuity the only fair or probable test is to be depend on causes external to the brain found in the greater or less difficulty of itself, though, from the nature of the arousing the sleeper by external action on case, less open to observation. The the senses of touch and hearing. Indilinks may escape observation, but we vidual temperament of body and mind, cannot hesitate in bringing these phenom- habits of life, and the immediate anteena under the general law of Continuity, cedents of sleep, are all concerned in this so universal throughout nature, organic matter. The Duke of Wellington, in that or inorganic, living or lifeless. This law, hour of his recorded sleep on the field of scarcely recognized in philosophy or sci- Salamanca, when the two armies were ence before the time of Leibnitz, is now closely pressing to their conflict, probareceiving confirmation from every new ably slept more soundly than any of the discovery, and becoming the interpreter of endless phenomena hitherto unexplained. Leibnitz himself applies it to the question of the suspension of thinking in sleep; deeming it impossible, on this consideration, that such entire suspension should ever really occur.

We shall speak more explicitly hereafter on the physiology of sleep as regards the physical changes concerned in producing or modifying it. But there are various other facts, natural or abnormal, belonging to the physiology of this function of life, which require previous notice some of them indeed so strangely anomalous as to have furnished food at once to sober philosophy and to the wildest dreams of credulity. We may best begin with what we may call the natural conditions of sleep, while admitting that these ever tend to graduate into more abnormal phenomena.

idlers of a city life at home. The Somnus agrestium lenis virorum of Horace, is more powerfully expressed by Shakespeare in describing the dreamless sleep of the day-hireling,

Who with a body fill'd and vacant mind,

Gets him to rest, cramm'd with distressful
Sleeps in Elysium, &c.

bread,

And who can forget that noble soliloquy
in the Second Part of "Henry IV.," where
the king upbraids sleep for deserting "the
perfumed chambers of the great," and
giving its repose to the wet sea-boy in the
midst of storms?

Wilt thou upon the high and giddy mast
Seal up the ship-boy's eyes and rock his brains
In cradle of the rude imperious surge?

We might well go on through the whole
of this wonderful passage. If forgotten
by anyone, it ought promptly to be re-
newed to memory.

The various epithets applied to sleep -profound sleep, heavy sleep, light sleep, broken sleep, &c. We need not dwell further on a fact, so express actual realities of state; but these so mingled familiar to common experience. But the with each other, so fitful in change, and diversity of forms which sleep assumes is so perplexed by the vagaries of dreams more interesting to the physiologist in its and disturbing causes from within and relation to the particular organs and funcwithout, that even the sleeper himself is tions affected by it. We have already algenerally at fault in defining them. "Iluded to this topic; one which, associated have not slept a wink," is often the piteous exclamation of the morning, when only some short portion of the night has been made wakeful and restless by disordered digestion, or one of those compulsory trains of thought which fasten pertinaciously on the mind, despite every effort to shake them off. But, though we cannot measure the amount of sleep by

as it is with the phenomena of dreams, offers a special mode of mental analysis as connected with material organization, and may even in certain cases be made the subject of experiment. It does not, indeed, carry us farther into the mystery than a similar analysis of the waking state. But in showing how the two states commingle and graduate into one other, it

serves as fresh proof of the unity of our | himself; but in this gradation of state, nature; and explains many of those and even in what may be deemed the anomalous conditions which seem to vio- soundest sleep, an observer without, if late this unity, and have furnished food diligent in his watch, will detect many for credulity in all ages.' curious changes going on; due to the influence of passing dreams, of nervous sensations from the action of the vital organs within, and even from bodily posture. These are the changes to which M. Maury's methods of observation, already mentioned, especially apply. They are abundantly furnished by those nights of broken and disordered sleep which must be counted among the ills of man, though too often only the penalty paid for his luxury or other faults of life.