Philosophy can only account for a few of the greater and more sensible events of this war; but must leave all the smaller and more delicate revolutions, as dependent on principles too fine and minute for her comprehension. SECTION IX. OF THE DIRECT PASSIONS. 'Tis easy to observe, that the passions, both direct and indirect, are founded on pain and pleasure, and that, in order to produce an affection of any kind, 'tis only requisite to present some good or evil. Upon the removal of pain and pleasure, there immediately follows a removal of love and hatred, pride and humility, desire and aversion, and of most of our reflective or secondary impressions. The impressions which arise from good and evil most naturally, and with the least preparation, are the _direct_ passions of desire and aversion, grief and joy, hope and fear, along with volition. The mind, by an _original_ instinct, tends to unite itself with the good, and to avoid the evil, though they be conceived merely in idea, and be considered as to exist in any future period of time. But supposing that there is an immediate impression of pain or pleasure, and _that_ arising from an object related to ourselves or others, this does not prevent the propensity or aversion, with the consequent emotions, but, by concurring with certain dormant principles of the human mind, excites the new impressions of pride or humility, love or hatred. That propensity which unites us to the object, or separates us from it, still continues to operate, but in conjunction with the _indirect_ passions which arise from a double relation of impressions and ideas. These indirect passions, being always agreeable or uneasy, give in their turn additional force to the direct passions, and increase our desire and aversion to the object. Thus, a suit of fine clothes produces pleasure from their beauty; and this pleasure produces the direct passions, or the impressions of volition and desire. Again, when these clothes are considered as belonging to ourself, the double relation conveys to us the sentiment of pride, which is an indirect passion; and the pleasure which attends that passion returns back to the direct affections, and gives new force to our desire or volition, joy or hope. When good is certain or probable, it produces _joy_. When evil is in the same situation, there arises _grief or sorrow_. When either good or evil is uncertain, it gives rise to _fear_ or _hope_, according to the degrees of uncertainty on the one side or the other. _Desire_ arises from good considered simply; and _aversion_ is derived from evil. The _will_ exerts itself, when either the good or the absence of the evil may be attained by any action of the mind or body.