e is a disease of the epileptic or
cataleptic kind, since the paroxysms of this young lady always began and
frequently terminated with convulsions; and though in its greatest degree
it has been called somnambulation, or sleep-walking, it is totally
different from sleep; because the essential character of sleep consists in
the total suspension of volition, which in reverie is not affected; and the
essential character of reverie consists not in the absence of those
irritative motions of our senses, which are occasioned by the stimulus of
external objects, but in their never being productive of sensation. So that
during a fit of reverie that strange event happens to the whole system of
nerves, which occurs only to some particular branches of them in those, who
are a second time exposed to the action of contagious matter. If the matter
of the small-pox be inserted into the arm of one, who has previously had
that disease, it will stimulate the wound, but the general sensation or
inflammation of the system does not follow, which constitutes the disease.
See Sect. XII. 3. 6. XXXIII. 2. 8.

10. The following is the definition or character of complete reverie. 1.
The irritative motions occasioned by internal stimuli continue, those from
the stimuli of external objects are either not produced at all, or are
never succeeded by sensation or attention, unless they are at the same time
excited by volition. 2. The sensitive motions continue, and are kept
consistent by the power of volition. 3. The voluntary motions continue
undisturbed. 4. The associate motions continue undisturbed.

Two other cases of reverie are related in Section XXXIV. 3. which further
evince, that reverie is an effort of the mind to relieve some painful
sensation, and is hence allied to convulsion, and to insanity. Another case
is related in Class III. 1. 2. 2.

* * * * *

SECT. XX.

OF VERTIGO.

1. _We determine our perpendicularity by the apparent motions of
objects. A person hood-winked cannot walk in a straight line. Dizziness
in looking from a tower, in a room stained with uniform lozenges, on
riding over snow._ 2. _Dizziness from moving objects. A whirling-wheel.
Fluctuations of a river. Experiment with a child._ 3. _Dizziness from
our own motions and those of other objects._ 4. _Riding over a broad
stream. Sea-sickness._ 5. _Of turning round on one foot. Dervises in
Turkey. Attention of t