than he was at falling asleep. This deeper function of the night, what
is it?

Sleep is, first of all, a filter, or sieve. It strains off the
impressions that engross, but not enrich us,--that superfluous
_material_ of experience which, either from glutting excess, or from
sheer insignificance, cannot be spiritualized, made human, transmuted
into experience itself. Every man in our day, according to the measure
of his sensibility, and with some respect also to his position, is
_mobbed_ by impressions, and must fight as for his life, if he escape
being taken utterly captive by them. It is our perpetual peril that
our lives shall become so sentient as no longer to be reflective or
artistic,--so beset and infested by the immediate as to lose all
amplitude, all perspective, and to become mere puppets of the present,
mere Chinese pictures, a huddle of foreground without horizon, or
heaven, or even earthly depth and reach. It is easy to illustrate this
miserable possibility. A man, for example, in the act of submitting
to the extraction of a tooth, is, while the process lasts, one of the
poorest poor creatures with whose existence the world might be taunted.
His existence is but skin-deep, and contracted to a mere point at that:
no vision and faculty divine, no thoughts that wander through eternity,
now: a tooth, a jaw, and the iron of the dentist,--these constitute, for
the time being, his universe. Only when this monopolizing, enslaving,
sensualizing impression has gone by, may what had been a point of pained
and quivering animality expand once more to the dimensions of a human
soul. Kant, it is said, could withdraw his attention from the pain of
gout by pure mental engagement, but found the effort dangerous to
his brain, and accordingly was fain to submit, and be no more than
a toe-joint, since evil fate would have it so. These extreme cases
exemplify a process of impoverishment from which we all daily suffer.