AND OF THE PHYSICAL SCIENCES. 



175 



light, others during the interval of darkness ; others, again, observe no regularity in 

 this respect, but take a certain portion of rest, with frequent interruptions, during 

 the twenty-four hours, all these variations of habit being in accordance with the 

 respective varieties of their economies, and in particular with the different natures of 

 their food. But some partake of a large proportion of sleep daily, while others are 

 content with a much less quantity, and some, also, enjoy but a limited amount afier 

 protracted activity. And here we are deficient in reasons, for this quantity of sleep 

 does by no means appear proportioned to the quantity of exercise sustained by the 

 respective animals, sleep or rest being ordinarily and rationally regarded as a cnm- 

 pensation to the animal powers for previous activity. The Swift and Swillow, 

 •which take both incessant and violent exercise during the long days of summer, take 

 only the same portion of sleep as the Sparrow or the Robin, which move only to the 

 adjoining gardens and homesteads throughout the day ; the Stormy Petrel, which 

 ■continues on the wing, and is ever changing the direction of its flight throughout the 

 tempest, and is for the most part in action at other times, seems to take but a very 

 flmall quantity of compensating rest and sleep. Birds of prey, which for the most 

 part are not obligated to use much exertion in the capture of their quarry, seem 

 nevertheless to devote a large proportion of time to repose. The Alligator, according 

 to report, indulges much in rest, although its actions are limited in comparison with 

 very many other creatures feeding and living similarly. Very many kinds of insects 

 whose spheres of activity are very circumscribed, apparently set apart a considerable 

 deal of time to sleep, or at least inertion. Sleep is enjoyed by creatures with differ- 

 ent degrees of perfection, some being awakened with the slightest noises, others al- 

 lowing themselves to be approached, and even touched or injured, before their faculties 

 are resuscitated; "the Rook," as Mr Knapp says, "seems rather to rest than 

 sleep. Pass what time I may in a road adjoining a rookery in this parish, 1 inevitably 

 hear many of them disturbing the quiet of the night, as if impatient to see the dawning 

 of the next day." The Alligator, it seems, may be approached quite near while it 

 sleeps, and from its colour, dimensions, and figure, very many persons have thus 

 been exposed to imminent peril. Perhaps, generally speaking, this unsusceptibility 

 to noise and intrusion, during repose, may be proportioned to the powers and courage 

 of the animal, for, though the Rook roosts high, and ought to be free from the ap- 

 prehension of danger, yet a variety of the weaker kinds of creatures need to be wary 

 and watchful, and surely are so. The Sedge-bird gives notire of this wakefulness, 

 by uttering its peculiar notes frequently on the mere passage of a person on a neigh- 

 bouring road, independently of any further interruption, such as throwing a stone 

 into the bush where it roosts, as Mr White and others have stated. If sleep be perfect 

 and healthy, the whole nervous system during this interval of rest is passive and 

 inert; thought and all mental action, together with sensation, are suspended; if the 

 two former are continued, one part only of the nervous system is at rest, if they are 

 continued, we see no demonstration of them, and if their action is supposed to be 

 partial, of what use would such imperfect action be? But there are fevT persons so 

 foolish as to conceive that dreams and other demonstrations of continued nervous 

 operation occur in a true state of nature, and consequ<;ntly it seems to follow, that 

 these are only concomitants of disease, or at least of depraved condition of system, 

 which is the same thing as disease, only in a less degree. Still the nervous system, 

 while we have seen that it enjoys its repose in varied extents, and in varied degrees of 

 perfection, in accordance, no doubt (though we are not able to trace these connexions 

 on all occasions), with the habits and economies of creatures, is found to be more sus- 

 ceptible of derangement and lesion in some domesticated animals than in others, for 

 it is in the domesticated state that disease nearly always occurs. We do not draw 

 this conclusion from the instance of our own species, because man seems to take 

 pains, by unsuited diet and depraved actions, to induce disease, and this has been per- 

 petuated through a succession of generations ; but the Dog is remarkably the subject 

 of dreams, while the Horse is seldom, if ever, so affected, but altogether the nervous 

 system is that most usually disordered and disorganized in domesticated and confined 

 animals; witness Palsy, Epilepsy, Mania, Hydrophobia, Deafness, Sec. In ourselvei 

 there are certain peculiarities of our dreams which, to weak-minded persons, suggest 

 a degree of importance respecting them, which it may be clearly shown they have no 

 right to. In the first place, it is not fair that any support should be granted to such 

 an idea, from the fact of dreams having in primitive ages been made use of as divine 

 instruments and intimations, because we have no grounds whatever for supposing that 

 in latter ages such manifestations have been vouchsafed to any members of our race, 

 or that we h.ive been favoured with such immediate and appreciable interferences and 

 demonstrations. Science is not called on to refute the errors of vulgar superstition, 

 or the chimerical delusions of religious fanatics. It is said, that if one should dream 

 a dream several times repeated, it is sure to be eventually verified ; but who will 

 stand forth to corroborate this assertion ? And without staying to lay stress on certain 

 points which furnish objections to the validity of such a belief, may not such occur- 

 rences be safely referred to the mind of the dreamer having dwelt for some time on 

 the subject of the dream, or on something analogous thereto, and we shall presently 

 •how that the mind is very apt in us to perform its offices in a partial, imperfect, and 

 incoherent manner during sleep, or rather our imperfect repose. Perhaps the most 

 important of the presumed supports to the prophetic nature of dreams, or a portion 

 of them, is drawn from the extraordinary dream of the celebrated Mr Newton, and 

 other cases of the same character ; but without entering into an inquiry of the parti- 

 culars oi these^ which would lead me further from my present argument than 1 should 

 wish, I will content myself by observing, thit since our sleep is so frequently unsound, 

 fspecially where the mind is in an habitually disturbed and excited state, as in the 

 case of Newton, and since it does appear, as I shall presently again state, that unsound 

 ileep IS compatible with a greater or less development of the imaginative, and even of 

 the reasoning powers also, so it is not more wonderful that in such kind of sleep, 

 partaken of by persons of a disturbed and nervous habit, the mind should foresee events 

 connected essentially with its immediate character, than that the same prophetic in- 

 dulgence of the mind, during a waking state, should actually receive a verification ; 

 " for, as Mr Mayo observes, " the mind in dreaming moves in its accustomed 

 channels. Still, though I am disposed, from the general analogy of the argument, 

 to exclude all credit in the importance and prophetic character of dreams, 1 feel that 



it would be ra=h and indecorous to deny the possibility that in such cases as Mr 

 Newton's a divine influence may have been interposed. 



It appears to me that true natural sleep excludes at once consciousness and thought, 

 that consciousness is capable of being brought into action on the application of sti- 

 muli, or excitants of the nervous system, with various d-:'grees uf ease in diffi-rent in- 

 dividuals, ju'it as we have seen animals, more or less readily aroused from sleep on 

 the intrusion of noise, contact, &c. We usually find that on the removal of the 

 intrusions to our dormant consciousness, the latter again withdraws itself to rest ; at 

 other times, according to the condition of the health of persons, these intrusions con- 

 stitute the basis of some imaginative flights in their subsequent imperfect sleep. The 

 movement of the limbs, in order to attain more convenient posture?, together with 

 other momentary demonstrations of consciousness, serve only to show incidental in- 

 terruptions to our repose, induced by painful impressions, but yet so transitory and 

 incomplete, as seldom to leave any trace of it on the memory. With regard to 

 mental operations during sleep (imperfect sleep), they are excited by various causes, 

 and are in themselves different in their natures ; some of the causes of dreams will 

 sufficiently account for the character they evince ; a disordered state of stomach from 

 repletion, ill-adaj'ted food, &c., will draw forth the imagination to luxurious repasts 

 or revellings, in the sense of taste; the receipt of injuries or calumnies will often 

 suggest dreams of a vindictive or disputative character ; the study of some abstruse 

 or impoitant subject, on which we may be intently bent, will occasionally be found the 

 subject of our druams ; in all of which cases we usually find that the mind occupies itself 

 upon them in a desultory and incoherent manner, probably combining objects of im- 

 portance with those of an opposite nature, associating the ludicrous with the grave, 

 or bringing some unconnected and indifferent materials into opposition with a con- 

 nected train of thought on the realities of some ]ireceding day, or on some future 

 probabilitifs : On the contrary, at times, though rarely, the mind will act as perfectly 

 as though the dreamer were awake, and the senses themselves receiving no actual 

 impressions by which the mind is ordinarily obstructed during iis investigations, the 

 processes of the imagination and of reasoning are conducted with more than usual 

 speed, perspicuity, method, and perfection. It has happened to me when my mind 

 was occupied in retaining a deal of relative anatomy, tlian which nothing can be 

 more arduous, to have dreamed with the utmost accuracy and with great profit, the 

 whole of what I had been engaged in learning on previous days. I have also at 

 times been enabled in my sleep to repeat the various steps of an argument or theory, 

 respecting which I had been interested At seasons when the mind is occupied for 

 many successive days in the contemplation of some given subject, and in lookino^ for- 

 ward to future results, it cannot be deemed extraordinary, that on the same consecu- 

 tive nights there should be a repetition of certain prospective images, or that these 

 fancies of our sleep being the reflected images of our previous waking thoughts, 

 when reason guided our apprehensions, should on some future occasion receive their 

 realization. 



The condition of persons who think or recapitulate correctly in what is ordinarily 

 termed their sleep, is not essentially different from their state while in a reverie, for, 

 in the latter, consciousness, sensation, and motion (or the consciousness of it), are in 

 a great measure suspended, and it seems that in this species of repose the mind acts 

 while consciousness, sense, and the muscular fibre, are recruiting their powers. It 

 is, in my estimation, an error to attribute real, perfect, and healthy sleep to persons 

 who are in the habit of dreaming incoherencies, and much more so to allow it to those 

 in whom the mental operations are skilfully carried on, because, if sleep be a destined 

 interval between the seasons of mental and bodily exertion, it is certainly not attained 

 by those who are observed to use mure or less muscular efforts in what is termed 

 their sleep, nor by those in whom ratiocination, exertion of memory, or excited in- 

 terest, is remarked ; neither by fair inference is it enjoyed by those who dream inco- 

 herently, or indulge their fancies vaguely and loosely in the blandishments of sense. 

 The mind very commonly in our sleep occupies itself on the subjects which last en- 

 gaged our attention previously to our repose, and if we fall asleep with the desire to 

 awake at an hour earlier than has been our habit, that object is kept in view through- 

 out the night, and we wake at the time desired. On one occasion I was a som- 

 nambulist ; in my dream I fancied 1 had been called on by a knock at the door 

 to lot some one into the house ; I threw back the bed-clothes, opened my door, 

 avoided, by means of ray sight, objects that might impede rae, descended a flight 

 of stairs, holding by the bannisters, unbolted the street door, and returned with 

 care to my bedroom, these facts having been brought to my remembrance by find- 

 ing the door unsecured in the morning. Now, in this and the preceding cases, it 

 seems contradictory to suppose the occurrence of actual sleep, for, besides the 

 evidence they bear of mere partial repose, it is seen, that where the person rests 

 with the intention of being engaged the next day on an occupation of importance, 

 where the dream is unusually exciting, where there is a wish to awake sooner 

 than usual, and where somnambulism occurs, the sleeper is, ccEieria paribus, 

 awakened with unusual ease ; moreover, many persons dream but seldom, and can 

 then attribute the circumstance to some evident cause ; lastly, many partake of a 

 sleep in which they have some very indistinct perceptions of passing occurrences ; in 

 all these instances, the conclusion of sleep being void of consciousness and thought in 

 a healthy state of body, and connected with the same by reason of disease or moral 

 excitement, being apparently unavoidable. Dreams have reference to past facts, im- 

 pressions, and mental piospects of the future ; they are mostly reflected images of 

 realities we had either experienced, or wrought up by our fancies in a waking state. 

 They who advocate the prophetic nature of dreams must acquaint us whether they 

 were realized to them in a strict and satisfactory manner with relation to the dreams. 

 They must say also why all dreams are not prophetic, why so large a proportion con- 

 sist of incoherent materials, and especially they must explain why dreams, seemingly 

 important, and quite consistent in detail, are never verified. 



If the above named opinions relative to sleep and dreaming are correct, those of 

 Mayo, Elliotson, and others, must be wrong. Mr Rennie, in " Habits of Birds," 

 after allowing that the Redbreast, Restart, and other birds, occasionally sing at night, 

 mentions a supposititious case of a Dunnock singing at ten p.m. wlt'tle asleep. That 

 caged birds may do thus, is what I will allow as readily as Mr Kennie, but is it not 



