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 counteract a violent passion in prosecution of their interests and designs; 'tis 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 solicitations 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. SECTION IV. OF THE CAUSES OF THE VIOLENT PASSIONS. There is not in philosophy a subject of more nice speculation than this, of the different _causes_ and _effects_ of the calm and violent passions. 'Tis evident, passions influence not the will in proportion to their violence, or the disorder they occasion in the temper; but, on the contrary, that when a passion has once become a settled principle of action, and is the predominant inclination of the soul, it commonly produces no longer any sensible agitation. As repeated custom and its own force have made every thing yield to it, it directs the actions and conduct without that opposition and emotion which so naturally attend every momentary gust of passion. We must, therefore, distinguish betwixt a calm and a weak passion; betwixt a violent and a strong one. But notwithstanding this, 'tis certain that, when we would govern a man, and push him to any action, 'twill commonly be better policy to work upon the violent than the calm passions, and rather take him by his inclination, than what is vulgarly called his _reason_. We ought to place the object in such particular situations as are proper to increase the violence of the passion. For we may observe, that all depends upon the situation of the object, and that a variation in this particular will be able to change the calm and the violent passions into each other. Both these kinds of passions pursue good, and avoid evil; and both of them are increased or diminished by the increase or diminution of the good or evil. But herein lies the difference betwixt them: the same good, when near, will cause a violent passion, which, when remote, produces only a calm one. As this subject belongs very properly to the present question concerning the will, we shall here examine it to the bottom, and shall consider some of those