It is natural for one, that does not examine objects with a strict philosophic eye, to imagine, that those actions of the mind are entirely the same, which produce not a different sensation, and are not immediately distinguishable to the feeling and perception.  Reason, for instance, exerts itself without producing any sensible emotion; and except in the more sublime disquisitions of philosophy, or in the frivolous subtilties of the school, scarce ever conveys any pleasure or uneasiness.  Hence it proceeds, that every action of the mind, which operates with the same calmness and tranquillity, is confounded with reason by all those, who judge of things from the first view and appearance.  Now it is certain, there are certain calm desires and tendencies, which, though they be real passions, produce little emotion in the mind, and are more known by their effects than by the immediate feeling or sensation.  These desires are of two kinds; either certain instincts originally implanted in our natures, such as benevolence and resentment, the love of life, and kindness to children; or the general appetite to good, and aversion to evil, considered merely as such.  When any of these passions are calm, and cause no disorder in the soul, they are very readily taken for the determinations of reason, and are supposed to proceed from the same faculty, with that, which judges of truth and falshood.  Their nature and principles have been supposed the same, because their sensations are not evidently different.

Beside these calm passions, which often determine the will, there are certain violent emotions of the same kind, which have likewise a great influence on that faculty.  When I receive any injury from another, I often feel a violent passion of resentment, which makes me desire his evil and punishment, independent of all considerations of pleasure and advantage to myself.  When I am immediately threatened with any grievous ill, my fears, apprehensions, and aversions rise to a great height, and produce a sensible emotion.

The common error of metaphysicians has lain in ascribing the direction of the will entirely to one of these principles, and supposing the other to have no influence.  Men often act knowingly against their interest:  For which reason the view of the greatest possible good does not always influence them.  Men often counter-act a violent passion in prosecution of their interests and designs:  It is not therefore the present uneasiness alone, which determines them.  In general we may observe, that both these principles operate on the will; and where they are contrary, that either of them prevails, according to the general character or present disposition of the person.  What we call strength of mind, implies the prevalence of the calm passions above the violent; though we may easily observe, there is no man so constantly possessed of this virtue, as never on any occasion to yield to the sollicitations of passion and desire.  From these variations of temper proceeds the great difficulty of deciding concerning the actions and resolutions of men, where there is any contrariety of motives and passions.