me is wholly dependent upon the rapidity with which
impressions succeed one another. Were we capable of receiving only
one impression an hour, like a bell struck every hour with a hammer,
the ordinary term of life would seem very short. On the other hand,
if our time sense were always as acute as it is in dreams, uncounted
aeons would seem to be lived through in the interval between
childhood and old age.

Imagine a music machine so cunningly constructed and adjusted as not
only to sound each note and chord in its proper sequence and relation,
but to regulate also the duration of the sound vibration. If this
machine were operated in such a manner as to play, in a single
second of time, the entire overture of an opera which would normally
occupy half an hour, we should hear only an unintelligible noise a
second long. This would be due to no defect in the _sound-producing_
mechanism, but to the limitations of the _sound-receiving_ mechanism,
our auditory apparatus. Could this be altered to conform to the
unusual conditions--could it capture and convey to consciousness
every note of the overture in a second of time--that second would
seem to last half an hour, provided that every other criterion for
the measurement of duration were denied for the time being.

Now dreams _seem_ long: we only discover afterwards and by accident
their almost incredible brevity. May we not--must we not--infer from
this that the body is an organ of many stops and more than one
keyboard, and that in sleep it gives forth this richer music. The
theory of a higher-dimensional existence during sleep accounts in
part for the great longing for sleep. "What is it that is much
desired by man, but which they know not while possessing?" again
asks Leonardo. "It is sleep," is his answer. This longing for sleep
is more than a physical longing, and the refreshment it brings is
less of the flesh than of the spirit. It is possible to withstand
the deprivation of food and water longer and better than the
deprivation of sleep. Its recuperative power is correspondingly
greater.

Experiments have been made with mature University students by which
they have been kept awake ninety-six hours. When the experiments
were finished, the young men were allowed to sleep themselves out,
until they felt they were thoroughly rested. All awoke from a long
sleep completely refreshed, but the one who took longest to restore
himself from his protracted vigil slept only one-thi