or in
consequence of volition, becomes now in some degree accumulated, and
renders the internal or immediate organs of sense more easily excitable by
the other sensorial powers. Thus in respect to the eye, the irritation from
external stimuli, and the power of volition during our waking hours,
elevate the eye-lids, adapt the aperture of the iris to the quantity of
light, the focus of the crystalline humour, and the angle of the optic
axises to the distance of the object, all which perpetual activity during
the day expends much sensorial power, which is saved during our sleep.

Hence it appears, that not only those parts of the system, which are always
excited by internal stimuli, as the stomach, intestinal canal, bile-ducts,
and the various glands, but the organs of sense also may be more violently
excited into action by the irritation from internal stimuli, or by
sensation, during our sleep than in our waking hours; because during the
suspension of volition, there is a greater quantity of the spirit of
animation to be expended by the other sensorial powers. On this account our
irritability to internal stimuli, and our sensibility to pain or pleasure,
is not only greater in sleep, but increases as our sleep is prolonged.
Whence digestion and secretion are performed better in sleep, than in our
waking hours, and our dreams in the morning have greater variety and
vivacity, as our sensibility increases, than at night when we first lie
down. And hence epileptic fits, which are always occasioned by some
disagreeable sensation, so frequently attack those, who are subject to
them, in their sleep; because at this time the system is more excitable by
painful sensation in consequence of internal stimuli; and the power of
volition is then suddenly exerted to relieve this pain, as explained Sect.
XXXIV. 1. 4.

There is a disease, which frequently affects children in the cradle, which
is termed ecstasy, and seems to consist in certain exertions to relieve
painful sensation, in which the voluntary power is not so far excited as
totally to awaken them, and yet is sufficient to remove the disagreeable
sensation, which excites it; in this case changing the posture of the child
frequently relieves it.

I have at this time under my care an elegant young man about twenty-two
years of age, who seldom sleeps more than an hour without experiencing a
convulsion fit; which ceases in about half a minute without any subsequent
stupor. Large dos