material substance, or both, some secret mechanism or structure of
parts, upon which the effect depends, and which, being entirely unknown
to us, renders the power or energy of the will equally unknown and
incomprehensible?

Volition is surely an act of the mind, with which we are sufficiently
acquainted. Reflect upon it. Consider it on all sides. Do you find
anything in it like this creative power, by which it raises from nothing
a new idea, and with a kind of _Fiat_, imitates the omnipotence of its
Maker, if I may be allowed so to speak, who called forth into existence
all the various scenes of nature? So far from being conscious of this
energy in the will, it requires as certain experience as that of which
we are possessed, to convince us that such extraordinary effects do ever
result from a simple act of volition.

54. The generality of mankind never find any difficulty in accounting
for the more common and familiar operations of nature--such as the
descent of heavy bodies, the growth of plants, the generation of
animals, or the nourishment of bodies by food: But suppose that, in all
these cases, they perceive the very force or energy of the cause, by
which it is connected with its effect, and is for ever infallible in its
operation. They acquire, by long habit, such a turn of mind, that, upon
the appearance of the cause, they immediately expect with assurance its
usual attendant, and hardly conceive it possible that any other event
could result from it. It is only on the discovery of extraordinary
phaenomena, such as earthquakes, pestilence, and prodigies of any kind,
that they find themselves at a loss to assign a proper cause, and to
explain the manner in which the effect is produced by it. It is usual
for men, in such difficulties, to have recourse to some invisible
intelligent principle[13] as the immediate cause of that event which