[12] It may be pretended, that the resistance which we meet
with in bodies, obliging us frequently to exert our force, and
call up all our power, this gives us the idea of force and
power. It is this _nisus_, or strong endeavour, of which we are
conscious, that is the original impression from which this idea
is copied. But, first, we attribute power to a vast number of
objects, where we never can suppose this resistance or exertion
of force to take place; to the Supreme Being, who never meets
with any resistance; to the mind in its command over its ideas
and limbs, in common thinking and motion, where the effect
follows immediately upon the will, without any exertion or
summoning up of force; to inanimate matter, which is not
capable of this sentiment. _Secondly,_ This sentiment of an
endeavour to overcome resistance has no known connexion with
any event: What follows it, we know by experience; but could
not know it _a priori._ It must, however, be confessed, that
the animal _nisus,_ which we experience, though it can afford
no accurate precise idea of power, enters very much into that
vulgar, inaccurate idea, which is formed of it.

53. Shall we then assert, that we are conscious of a power or energy in
our own minds, when, by an act or command of our will, we raise up a new
idea, fix the mind to the contemplation of it, turn it on all sides, and
at last dismiss it for some other idea, when we think that we have
surveyed it with sufficient accuracy? I believe the same arguments will
prove, that even this command of the will gives us no real idea of force
or energy.

_First,_ It must be allowed, that, when we know a power, we know that