blinds us; which means that our eyes have for a time lost their
ability to appreciate light. After eating a quantity of honey, we
are apt to think our tea is without sugar. The phrase "a deafening
roar," implies that men find a very loud sound temporarily
incapacitates them for hearing faint ones. To a hand which has
for some time carried a heavy body, small bodies afterwards lifted
seem to have lost their weight. Now, the truth at once recognized
in these, its extreme manifestations, may be traced throughout.
It may be shown that alike in the reflective faculties, in the
imagination, in the perceptions of the beautiful, the ludicrous,
the sublime, in the sentiments, the instincts, in all the mental
powers, however we may classify them-action exhausts; and that in
proportion as the action is violent, the subsequent prostration is
great.

60. Equally, throughout the whole nature, may be traced the law
that exercised faculties are ever tending to resume their original
state. Not only after continued rest, do they regain their full
power not only do brief cessations partially reinvigorate them; but
even while they are in action, the resulting exhaustion is ever
being neutralized. The two processes of waste and repair go on
together. Hence with faculties habitually exercised--as the senses
of all persons, or the muscles of any one who is strong--it happens
that, during moderate activity, the repair is so nearly equal to
the waste, that the diminution of power is scarcely appreciable;
and it is only when the activity has been long continued, or has
been very violent, that the repair becomes so far in arrear of
the waste as to produce a perceptible prostration. In all cases,
however, when, by the action of a faculty, waste has been incurred,
_some_ lapse of time must take place before full efficiency can be