e subcutaneous muscles exerted to relieve it are very general; and, if
the pain is still greater, a chattering of the teeth is added, the more
suddenly to exhaust the sensorial power, and because the teeth are very
sensible to cold.

These convulsive motions are nevertheless restrainable by violent voluntary
counteraction; and as their intervals are owing to the pain of cold being
for a time relieved by their exertion, they may be compared to laughter,
except that there is no interval of pleasure preceding each moment of pain
in this as in the latter.

M. M. See I. 2. 2. 1.

3. _Clamor._ Screaming from pain. The talkative animals, as dogs, and
swine, and children, scream most, when they are in pain, and even from
fear; as they have used this kind of exertion from their birth most
frequently and most forcibly; and can therefore sooner exhaust the
accumulation of sensorial power in the affected muscular or sensual organs
by this mode of exertion; as described in Sect. XXXIV. 1. 3. This facility
of relieving pain by screaming is the source of laughter, as explained
below.

4. _Risus._ The pleasurable sensations, which occasion laughter, are
perpetually passing into the bounds of pain; for pleasure and pain are
often produced by different degrees of the same stimulus; as warmth, light,
aromatic or volatile odours, become painful by their excess; and the
tickling on the soles of the feet in children is a painful sensation at the
very time it produces laughter. When the pleasurable ideas, which excite us
to laugh, pass into pain, we use some exertion, as a scream, to relieve the
pain, but soon stop it again, as we are unwilling to lose the pleasure; and
thus we repeatedly begin to scream, and stop again alternately. So that in
laughing there are three stages, first of pleasure, then pain, then an
exertion to relieve that pain. See Sect. XXXIV. 1. 3.

Every one has been in a situation, where some ludicrous circumstance has
excited him to laugh; and at the same time a sense of decorum has forbid
the exertion of these interrupted screams; and then the pain has become so
violent, as to occasion him to use some other great action, as biting his
tongue, and pinching himself, in lieu of the reiterated screams which
constitute laughter.

5. _Convulsio._ Convulsion. When the pains from defect or excess of motion
are more distressing than those already described, and are not relievable
by such partial exertions, as in screaming,