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MEDICAL IMPORTANCE OF DREAMS.

the muscles of his arms and feet, that he had expended a similar amount of nervous power as if the muscles of both legs and arms had been exercised under similar circumstances whilst under the perfect volition of consciousness.'—Journal of Psychological Medicine, vol. ix. Oct., 1856.

A STUDY OF COMMON INTEREST.

SIR HENRY HOLLAND, M.D., ETC.

'It concerns not less the physician than the metaphysical inquirer to learn all the conditions of this remarkable function of life, and the causes by which they are modified. Remarkable it may fitly be called; for what more singular than that nearly a third part of existence should be passed in a state thus far separate from the external world!a state in which consciousness and sense of identity are scarcely maintained; where memory and reason are equally disturbed; and yet, with all this, where the fancy works variously and boldly, creating images and impressions which are carried forwards into waking life, and blending themselves deeply and strongly with every part of our mental existence. It is the familiarity with this great func

• ""Half our days we pass in the shadow of the earth, and the brother of death extracteth a third part of our lives,” saith Sir

PHYSIOLOGY OF SLEEP.

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tion of our nature which prevents our feeling how vast is the mystery it involves; how closely linked with all the phenomena of mental derangement, whencesoever produced; and, yet further, how singularly shadowing forth to our conception the greater and more lasting changes the mind may undergo without loss of its individuality.

'I am not sure that the subject, in its medical relations, has even yet received all the notice it deserves. Much knowledge, indeed, has been gained of late by looking more closely into the physical connections of sleep with other actions of the body, and particularly with those functions of the nervous system to which it is most intimately allied. But there is still scope for a few remarks having reference, partly to the physiology of sleep, and partly to its connection with the various forms and treatment of disease.

'It is singular that in a state so familiar, and filling so large a portion of the term of life, it should yet be difficult to distinguish that which is the most perfect condition of sleep-the furthest removed from the waking state. No certain proof can be had of this from our own recollections, nor from the feelings on awakening. Both depend more or less on the manner in which we are aroused from it. The best proofs, however

Thomas Browne; a writer whose genius and eloquence give him a high place in English literature, as well as in that of the profession to which he belonged.'

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NO PROOF OF A NEGATIVE.

ambiguous, are derived from the observation of those around. That may be presumed generally the soundest sleep in which there is most complete tranquillity of the bodily organs commonly dependent on the will. Sensation, the other great function of the brain involved, furnishes evidence to the same point in the varying effect of stimuli applied to the senses when thus closed. And this test might, perhaps, be most certain were it not that we have cause to believe the different senses to be unequally under this state even at the same moment of time. And further, there is ambiguity from the passage of sleep into coma, through gradations which cannot be defined by any limits we are competent to draw.*

'Evidence by ready tests as to the soundness of sleep is often of value in practice, both in reference to the point last mentioned, and because the physician is very liable to be misled by the error of the patient himself on the subject. The best proof which the latter can give is the absence of consciousness of having dreamed. This, however, does not render it certain that dreams have not existed. The observation of others, and the

'Aristotle, towards the end of his book, IIepi 'Evvπviwv, has some curious remarks on the subject, well illustrated by examples. All his writings on this and other intellectual collateral topics deserve much more intimate perusal than is given to them at the present day.'

SLEEP NEVER ABSOLUTELY DREAMLESS.

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recollections often suggested afterwards of those of which there has been no memory at the time, prove it to be wholly otherwise. The question as to this point, indeed, is one that has been much debated, and a decisive answer is very difficult. But I hold it as

more probable that no part of sleep is without some condition of dreaming: that is, without images present to the individual consciousness, and trains of thought founded thereon, however vague and unreal in themselves, and however slight or null the recollection they carry on to our waking existence. To believe it otherwise is to suppose two different states of sleep, more remote from each other than we can well conceive any two conditions of the same living being: one, in which sensations, thoughts, and emotions are present in activity and unceasing change; another, in which there is absence or nullity of every function of mind-annihilation, in fact, for the time, of all that is not merely organic life. Though we cannot disprove the latter, and must admit the difficulty of explaining the sleep of a new-born infant in any other sense, yet it is on the whole more reasonable to suppose that no state of sleep is utterly without dreaming, the diversity being testified chiefly (though imperfectly, as far as consciousness is concerned) by the varying recollections of

"This question is noticed expressly by Aristotle. Lord Brougham, in his "Discourse on Natural Theology," holds an

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FLUCTUATING CONDITION.

what has passed through the mind during the time in question.

However this be, it is important in all our reasonings, practical and theoretical, upon sleep, to keep in mind that it is not a unity of state with which we are dealing, but a series of fluctuating conditions of which no two moments, perhaps, are strictly alike. It may be affirmed that these variations extend from complete wakefulness to the most perfect sleep of which we have cognisance, either by outward or inward signs. In the symptoms, as well as the treatment of disease, attention to this point is of material consequence; and it assists us, far beyond any other view, in explaining many of the seeming anomalies in this great function of life.

'Looking to what may be termed the passage between sleep and waking, it is singular with what rapidity and facility these states often alternate with each other. It is in the act of transition that we may best authenticate our knowledge of these phenomena; and the most ordinary incidents are full of instruction if the mind be directed to observe them. One familiar instance is that of being on horseback when much wearied from

opinion the reverse of that stated above; and vindicates, with his wonted power of argument, the belief that we dream during the time of transition into and out of sleep, when the two states are graduating into each other.'