r have been as strongly insisted on. In order
to shew the fallacy of all this philosophy, I shall endeavour to prove
first, that reason alone can never be a motive to any action of the
will; and secondly, that it can never oppose passion in the direction of
the will.

The understanding exerts itself after two different ways, as it judges
from demonstration or probability; as it regards the abstract relations
of our ideas, or those relations of objects, of which experience only
gives us information. I believe it scarce will be asserted, that the
first species of reasoning alone is ever the cause of any action. As its
proper province is the world of ideas, and as the will always places
us in that of realities, demonstration and volition seem, upon that
account, to be totally removed, from each other. Mathematics, indeed,
are useful in all mechanical operations, and arithmetic in almost every
art and profession: But it is not of themselves they have any influence:
Mechanics are the art of regulating the motions of bodies to some
designed end or purpose; and the reason why we employ arithmetic in
fixing the proportions of numbers, is only that we may discover the
proportions of their influence and operation. A merchant is desirous of
knowing the sum total of his accounts with any person: Why? but that he
may learn what sum will have the same effects in paying his debt, and
going to market, as all the particular articles taken together. Abstract
or demonstrative reasoning, therefore, never influences any of our
actions, but only as it directs our judgment concerning causes and
effects; which leads us to the second operation of the understanding.

It is obvious, that when we have the prospect of pain or pleasure from
any object, we feel a consequent emotion of aversion or propensity,
and are carryed to avoid or embrace what will give us this uneasines or
satisfaction. It is also obvious, that this emotion rests not here, but
making us cast our view on every side, comprehends whatever objects are
connected with its original one by the relation of cause and effect.
Here then reasoning takes place to discover this relation; and according
as our reasoning varies, our actions receive a subsequent variation. But
it is evident in this case that the impulse arises not from reason, but
is only directed by it. It is from the prospect of pain or pleasure that
the aversion or propensity arises towards any object: And these emotions
exte