the surrounding objects. Nor was it certain that any irritative motions
succeeded the stimulus of external objects, till the reverie became less
complete, and then she could walk about the room without running against
the furniture of it. Afterwards, when the reverie became still less
complete from the use of opium, some few irritations were at times
succeeded by her attention to them. As when she smelt at a tuberose, and
drank a dish of tea, but this only when she seemed voluntarily to attend to
them.

6. In common life when we listen to distant sounds, or wish to distinguish
objects in the night, we are obliged strongly to exert our volition to
dispose the organs of sense to perceive them, and to suppress the other
trains of ideas, which might interrupt these feeble sensations. Hence in
the present history the strongest stimuli were not perceived, except when
the faculty of volition was exerted on the organ of sense; and then even
common stimuli were sometimes perceived: for her mind was so strenuously
employed in pursuing its own trains of voluntary or sensitive ideas, that
no common stimuli could so far excite her attention as to disunite them;
that is, the quantity of volition or of sensation already existing was
greater than any, which could be produced in consequence of common degrees
of stimulation. But the few stimuli of the tuberose, and of the tea, which
she did perceive, were such, as accidentally coincided with the trains of
thought, which were passing in her mind; and hence did not disunite those
trains, and create surprise. And their being perceived at all was owing to
the power of volition preceding or coinciding with that of irritation.

This explication is countenanced by a fact mentioned concerning a
somnambulist in the Lausanne Transactions, who sometimes opened his eyes
for a short time to examine, where he was, or where his ink-pot stood, and
then shut them again, dipping his pen into the pot every now and then, and