This repose is in contrast with a state of _waking_, that activity of mind in which ideas are constantly chasing each other like the waves of ocean; the mode of displacing one idea being by the excitement of another in its place.
In that state of sound sleep which overcomes children, whose tender brains are soon tired, or old persons whose brains are _worn_, and in persons of little reflection,—the mind is perfectly passive, and its manifestations cease.
So writes Professor Stewart,—that there was a total suspension of volition during sleep, as regards its influence over mental or corporeal faculties; and I may even adduce a scrap from Burton, although I am an admirer of the quaint old compiler for little else than his measureless industry:—
“Sleep is a rest or binding of the outward senses, and of the common sense, for the preservation of body and soul. Illigation of senses proceeds from an inhibition of spirits, the way being stopped by which they should come; this stopping is caused by vapours arising out of the stomach, filling the nerves by which the spirits should be conveyed. When these vapours are spent, the passage is open, and the spirits perform their accustomed duties: so that _waking_ is the _action_ and _motion_ of the senses, which the spirits, dispersed over all parts, cause.”
ASTR. But is volition always suspended even in sound sleep? Was it not the opinion of Berkley, that the mind even then was _percipient_? How else can we account for the waking exactly at one predetermined hour? If we retire to sleep at the latest hour, or oppressed with fatigue, so strong an impression is produced in our mind, that the breaking of our sleep is almost at the given moment.
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.