circumstances and situations of objects, which render a passion either calm or violent. 'Tis a remarkable property of human nature, that any emotion which attends a passion, is easily converted into it, though in their natures they be originally different from, and even contrary to, each other. 'Tis true, in order to make a perfect union among the passions, there is always required a double relation of impressions and ideas; nor is one relation sufficient for that purpose. But though this be confirmed by undoubted experience, we must understand it with its proper limitations, and must regard the double relation as requisite only to make one passion produce another. When two passions are already produced by their separate causes, and are both present in the mind, they readily mingle and unite, though they have but one relation, and sometimes without any. The predominant passion swallows up the inferior, and converts it into itself. The spirits, when once excited, easily receive a change in their direction; and 'tis natural to imagine this change will come from the prevailing affection. The connexion is in many respects closer betwixt any two passions, than betwixt any passion and indifference. When a person is once heartily in love, the little faults and caprice of his mistress, the jealousies and quarrels to which that commerce is so subject, however unpleasant, and related to anger and hatred, are yet found to give additional force to the prevailing passion. 'Tis a common artifice of politicians, when they would affect any person very much by a matter of fact, of which they intend to inform him, first to excite his curiosity, delay as long as possible the satisfying it, and by that means raise his anxiety and impatience to the utmost, before they give him a full insight into the business. They know that his curiosity will precipitate him into the passion they design to raise, and assist the object in its influence on the mind. A soldier advancing to the battle, is naturally inspired with courage and confidence, when he thinks on his friends and fellow-soldiers; and is struck with fear and terror, when he reflects on the enemy. Whatever new emotion, therefore, proceeds from the former, naturally increases the courage; as the same emotion, proceeding from the latter, augments the fear, by the relation of ideas, and the conversion of the inferior emotion into the predominant. Hence it is, that in martial discipline, the uniformity and lustre of our habit, the regularity of our figures and motions, with all the pomp and majesty of war, encourage ourselves and allies; while the same objects in the enemy strike terror into us, though agreeable and beautiful in themselves.