efforts of volition, in the pursuit of some interesting train of ideas, we
cease to be conscious of our existence, are inattentive to time and place,
and do not distinguish this train of sensitive and voluntary ideas from the
irritative ones excited by the presence of external objects, though our
organs of sense are furnished with their accustomed stimuli, till at length
this interesting train of ideas becomes exhausted, or the appulses of
external objects are applied with unusual violence, and we return with
surprise, or with regret, into the common track of life. This is termed
reverie or studium.

In some constitutions these reveries continue a considerable time, and are
not to be removed without greater difficulty, but are experienced in a less
degree by us all; when we attend earnestly to the ideas excited by volition
or sensation, with their associated connexions, but are at the same time
conscious at intervals of the stimuli of surrounding bodies. Thus in being
present at a play, or in reading a romance, some persons are so totally
absorbed as to forget their usual time of sleep, and to neglect their
meals; while others are said to have been so involved in voluntary study as
not to have heard the discharge of artillery; and there is a story of an
Italian politician, who could think so intensely on other subjects, as to
be insensible to the torture of the rack.

From hence it appears, that these catenations of ideas and muscular
motions, which form the trains of reverie, are composed both of voluntary
and sensitive associations of them; and that these ideas differ from those
of delirium or of sleep, as they are kept consistent by the power of
volition; and they differ also from the trains of ideas belonging to
insanity, as they are as frequently excited by sensation as by volition.
But lastly, that the whole sensorial power is so employed on these trains
of complete reverie, that like the violent efforts of volition, as in