l or volition is supposed to be always in
our own power. But the will or voluntary power, acts always from motive, as
explained in Sect. XXXIV. 1. and in Class IV. 1. 3. 2. and III. 2. 1. 12.
which motive can frequently be examined previous to action, and balanced
against opposite motives, which is called deliberation; at other times the
motive is so powerful as immediately to excite the sensorial power of
volition into action, without a previous balancing of opposite motives, or
counter volitions. The former of these volitions is exercised in the common
purposes of life, and the latter in the exertions of epilepsy and insanity.

It is difficult _to think without words_, which however all those must do,
who discover new truths by reasoning; and still more difficult, when the
words in common use deceive us by their twofold meanings, or by the
inaccuracy of the ideas, which they suggest.

ADDITION V. OF FIGURE.

I feel myself much obliged by the accurate attention given to the first
volume of Zoonomia, and by the ingenious criticisms bestowed on it, by the
learned writers of that article both in the Analytical and English Reviews.
Some circumstances, in which their sentiments do not accord with those
expressed in the work, I intend to reconsider, and to explain further at
some future time. One thing, in which both these gentlemen seem to dissent
from me, I shall now mention, it is concerning the manner, in which we
acquire the idea of figure; a circumstance of great importance in the
knowledge of our intellect, as it shews the cause of the accuracy of our
ideas of motion, time, space, number, and of the mathematical sciences,
which are concerned in the mensurations or proportions of figure.

This I imagine may have in part arisen from the prepossession, which has
almost universally prevailed, that ideas are immaterial beings, and
therefore possess no properties in common with solid matter. Which I
suppose to be a fanciful hypothesis, like the stories of ghosts and
apparitions, which have so long amused, and still amuse, the credulous
without any foundation in nature.

The existence of our own bodies, and of their solidity, and of their
figure, and of their motions, is taken for granted in my account of ideas;
because the ideas themselves are believed to consist of motions or
configurations of solid fibres; and the question now proposed is, how we
become acquainted with the figures of bodies external to our organs of
s