ffects them; and the action of those
sphincters is then in consequence of this disagreeable sensation. So the
secretion of saliva, which in young children is copiously produced by
irritation, and drops from their mouths, is frequently attended with the
agreeable sensation produced by the mastication of tasteful food;, till at
length the sight of such food to a hungry person excites into action these
salival glands; as is seen in the slavering of hungry dogs.

The motions of those muscles, which are affected by lascivious ideas, and
those which are exerted in smiling, weeping, starting from fear, and
winking at the approach of danger to the eye, and at times the actions of
every large muscle of the body become causable by our sensations. And all
these motions are performed with strength and velocity in proportion to the
energy of the sensation that excites them, and the quantity of sensorial
power.

2. Many of the motions of our organs of sense, or ideas, that were
originally excited into action by irritation, become in like manner more
frequently causable by our sensations of pleasure or pain. These motions
are then termed the ideas of imagination, and make up all the scenery and
transactions of our dreams. Thus when any painful or pleasurable sensations
possess us, as of love, anger, fear; whether in our sleep or waking hours,
the ideas, that have been formerly excited by the objects of these
sensations, now vividly recur before us by their connection with these
sensations themselves. So the fair smiling virgin, that excited your love
by her presence, whenever that sensation recurs, rises before you in
imagination; and that with all the pleasing circumstances, that had before
engaged your attention. And in sleep, when you dream under the influence of
fear, all the robbers, fires, and precipices, that you formerly have seen
or heard of, arise before you with terrible vivacity. All these sensual
motions, like the muscular ones above mentioned, are performed with
strength and velocity in proportion to the energy of the sensation of
pleasure or pain, which excites them, and the quantity of sensorial power.

II. 1. Many of these muscular motions above described, that are most
frequently excited by our sensations, are nevertheless occasionally
causable by volition; for we can smile or frown spontaneously, can make
water before the quantity or acrimony of the urine produces a disagreeable
sensation, and can voluntarily masti