convulsions or insanity; or like the great activity of the irritative
motions in drunkenness; or of the sensitive motions in delirium; they
preclude all sensation consequent to external stimulus.

2. Those persons, who are said to walk in their sleep, are affected with
reverie to so great a degree, that it becomes a formidable disease; the
essence of which consists in the inaptitude of the mind to attend to
external stimuli. Many histories of this disease have been published by
medical writers; of which there is a very curious one in the Lausanne
Transactions. I shall here subjoin an account of such a case, with its
cure, for the better illustration of this subject.

A very ingenious and elegant young lady, with light eyes and hair, about
the age of seventeen, in other respects well, was suddenly seized soon
after her usual menstruation with this very wonderful malady. The disease
began with vehement convulsions of almost every muscle of her body, with
great but vain efforts to vomit, and the most violent hiccoughs, that can
be conceived: these were succeeded in about an hour with a fixed spasm; in
which one hand was applied to her head, and the other to support it: in
about half an hour these ceased, and the reverie began suddenly, and was at
first manifest by the look of her eyes and countenance, which seemed to
express attention. Then she conversed aloud with imaginary persons with her
eyes open, and could not for about an hour be brought to attend to the
stimulus of external objects by any kind of violence, which it was proper
to use; these symptoms returned in this order every day for five or six
weeks.

These conversations were quite consistent, and we could understand, what
she supposed her imaginary companions to answer, by the continuation of her
part of the discourse. Sometimes she was angry, at other times shewed much