The subject we have run through, appears not a little entertaining. It is extremely curious to observe, in many instances, a plurality of causes producing in conjunction a great pleasure: in other instances, not less frequent, no conjunction, but each cause acting in opposition. To enter bluntly upon a subject of such intricacy, might gravel an acute philosopher; and yet by taking matters in a train, the intricacy vanisheth. Next in order, according to the method proposed, come external effects. And this leads to passions in particular, which involving desire are the causes of action. Two coexistent passions that have the same tendency, must be similar. They accordingly readily unite, and in conjunction have double force; which must hold whether the two passions have the same or different causes. This is verified by experience; from which we learn, that different passions having the same end in view, impel the mind to action with united force. The mind receives not impulses alternately from these passions, but one strong impulse from the whole in conjunction. And indeed it is not easy to conceive what should bar the union of passions that have all of them the same tendency. Two passions having opposite tendencies, may proceed from the same object or cause considered in different lights. Thus a mistress may at once be the object both of love and resentment. Her beauty inflames the passion of love: her cruelty or inconstancy causes resentment. When two such passions coexist in the same breast, the opposition of their aim prevents any sort of union. They are not felt otherwise than in succession. And the consequence must be one of two things: the passions will balance each other, and prevent external action; or one of them will prevail, and accomplish its end. Guarini, in his _Pastor Fido_, describes beautifully the struggle betwixt love and resentment directed upon the same object.