Part 31

EV. I will answer you at present, Astrophel, only by analysis; it is not yet time to explain.

I may grant that there is some latent effect,—passive memory, if you will,—for we do not count the hours in sleep, and calculate our time by the clock; but we wake, and soon the bell strikes.

We have on record some very curious instances of the periodical recurrence of ideas in a waking state, the measurement of time being referrible to mental impression, mechanically established by constant habit.

There was an idiot once, who was in the habit of amusing himself constantly by counting the hours as they were struck on the clock. It chanced, after some time, that the works of the clock were injured, so that the striking for a time had ceased. The idiot, notwithstanding, continued to measure the day with perfect correctness, by counting and beating the hour. This is a story of Dr. Plott’s, in his History of Staffordshire.

There is one of more modern date, somewhat analogous to this.

I may quote Holy Writ in support of this passive condition of true sleep; nay, even its similitude to death. How often do we find allusions to sleep and death as synonymous! Sir Thomas Brown was impressed so deeply with this likeness, that he “did not dare to trust it without his prayers.” And the Macedonian, who wished for more worlds to conquer, confessed his sleep proved to him his mortality. I may quote ancient poetry also in my support. Homer and Virgil describe sleep as the “Brother of Death;” and, among the profane poets of later times, the same sublime association is traced of this

“Mortis imago—et simulacrum.”

Among the ancient allegories, sleep is portrayed as a female, with black unfolded wings,—in her left hand, a white child, the image of Sleep; in her right, a black child, the image of Death.

On the tomb of Cypselus, according to Pausanias, night is thus personified.

CAST. How true, then, was the thought of the first deep sleeper, on the sensation of slumber:—

“——There gentle sleep First found me, and with soft oppression seiz’d My drownéd sense, untroubled; tho’ I thought I then was passing to my former state, Insensible, and forthwith to dissolve.”

But how fearful is this resemblance which changes “tir’d nature’s sweet restorer” into a type of death! Pr’ythee, Evelyn, do not affright me thus, by clothing sleep with terror, as if it were disease and danger.

EV. Why tremble for the mortal sleep of the just and good, who will feel, with William Hunter, on their death-bed, “how pleasant and easy it is to die;” and with another moralist,—

“Oh what a wonder seems the fear of death, Seeing how gladly we all sink to sleep; Night following night!”

Fear not, Castaly; I do not term slumber and gentle sleep disease, but signs of health. Not so, however, many a profound sleep, and its advances towards coma; those results of exhaustion from excess, or from intense and direct narcotics, as opium sleep, and the paralyzing senselessness from extreme cold, as in the story of Sir Joseph Banks and Dr. Solander in the antarctic regions.

You are aware that many remedies in medicine may be so intense as to cause fatality: inflammation, too, is the restorative process of wounds, but if in excess it is fatal. Appetite also, to a certain degree, is healthy; but craving and thirst, its extremes, are proved, by suffering, to be morbid.

If the mind is composed to perfect rest, it is lulled to senselessness; then metaphysically we are said to sleep: the mind is not excited by thought, and, in consequence, its supply of arterial blood is less, the more rapid flow of which would be the cause of waking.

Within certain limits sleep is a remedy; but it becomes perilous when intense, or too much indulged. One eccentric physician, as we read in the learned Boërhave, even fancied sleep the natural condition of man, and was wont to yield to its influence during eighteen of the twenty-four hours; but apoplexy soon finished his experiment.

This negative quiescence (for sleep is not a positive state) allows the restoration of energy, and then we wake. Even the senses accumulate their power in sleep; the eye is dazzled by the light when we wake, from the sensitiveness imparted by this accumulation.

The conceits regarding the cause of sleep are so various, that if I were to discuss their merits I should only weary your patience, as I perceive I have already done.

Some have thought that sleep arose from certain conditions of the blood in the vessels and nerves of the brain; its congestion in the sinuses; or a reflux of a great portion of it towards the heart: the result of depressed nervous energy—exhaustion, fatigue, cold, and the influence of powerful narcotics, or the combustion of charcoal. Others, that sleep arises from the deposition of fresh matter on the brain, and its sudden pressure. Then we have the cerebral collapse of Cullen, and of Richerand; the deficiency of animal spirits of Haller; the diminished afflux of blood to the brain of Blumenbach; and the exhausted irritability of the Brunonian theory adopted by Darwin.

Where the truth lies I presume not to decide, but it is clear there is a necessity for the occasional repose of the mental organ:

“Non semper arcum Tendit Apollo.”

Watchfulness invariably reduces, even in the brute: the wild elephant is tamed by the perseverance of the hunter in keeping it constantly awake.

The mind, then, as it is manifested to us (for deeply important is it that we confound not the perfect and pure, because unembodied essence of the soul, with its combined existence in the brain—that union from which a thought is born), the mind cannot exert itself beyond a certain period without a sensation of fatigue in the brain, as palpable as the exhaustion from excessive muscular exertion. And this depends on a natural law, that organs after acting a certain given period, flag and lose their energy. Thus the first harbinger of sleep is the closing of the lids from languor, and relaxation of the muscles. Muscular fibre will, however, regain its expenditure by simple rest, requiring a certain period for this re-accumulation, like the charging of an electrical jar. Sleep, however, is not always a sequence of exhausted irritability of muscle; we may be too tired to sleep; and thought and memory also will keep the mind awake, and prevent nervous energy from renewing corporeal vigour.

The excitement of thought beyond certain limits is both painful and destructive, evincing its effects by various grades of mental disorder, from simple headache to confirmed mania. Our first ray of hope, in fever, is often the coming on of a quiet sleep, and in the sad cases of delirium tremens we must either sleep or die; the effort of philosophical determination to overcome the depression only adding to its intensity, as in the case of a person worn out by labour, in attempting to labour on. This conflict cannot be more pertinently exemplified than by some passages in the life of Collins, by one who knew him well:—

“He languished some years under that depression of mind which unchains the faculties without destroying them, and leaves reason the knowledge of right without the power of pursuing it. These clouds which he perceived gathering on his intellects, he endeavoured to disperse by travel, and passed into France; but found himself constrained to yield to his malady, and returned. His disorder was no alienation of mind, but general laxity and feebleness, a deficiency rather of his vital than intellectual powers. What he spoke wanted neither judgment nor spirit, but a few minutes exhausted him, so that he was forced to rest upon the couch, till a short cessation restored his powers, and he was again able to talk with his former vigour.”

I believe that sensibility and fatigue of mind, by inducing sleeplessness, may often be the source even of mania.