Upon a review of these reasonings, I cannot doubt of an entire victory; and therefore having proved, that all actions of the will have particular causes, I proceed to explain what these causes are, and how they operate.
SECT.

III OF THE INFLUENCING MOTIVES OF THE WILL Nothing is more usual in philosophy, and even in common life, than to talk of the combat of passion and reason, to give the preference to reason, and assert that men are only so far virtuous as they conform themselves to its dictates.

Every rational creature, it is said, is obliged to regulate his actions by reason; and if any other motive or principle challenge the direction of his conduct, he ought to oppose it, till it be entirely subdued, or at least brought to a conformity with that superior principle.

On this method of thinking the greatest part of moral philosophy, antient and modern, seems to be founded; nor is there an ampler field, as well for metaphysical arguments, as popular declamations, than this supposed pre-eminence of reason above passion.
The eternity, invariableness, and divine origin of the former have been displayed to the best advantage: The blindness, unconstancy, and deceitfulness of the latter 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.