But there is a decided principle of connexion between the two doctrines: whether or not it be a principle that will bear scrutiny, is another question. The two systems are identified with each other, simply by the annihilation of the notion of power both in the material and in the immaterial world. As we cannot find in physical causes any power to produce their effect, so when a man moves his arm to strike, or his tongue to reprimand, we have no notion of any _power_ being exercised; but we have an impression that certain impulses are followed, and we can no more suppose that it was at the choice of the individual whether, when these impulses or motives existed, they should or should not be obeyed, than that when the phenomenon called in the material world the cause, made its appearance, there could be any doubt of its being followed by the effect. The inference from this was, that human actions are as much the objects of inductive philosophy as the operations of nature; that they are equally regular, effect following cause as much in the operations of the passions as in those of the elements. Of the application of the theory to his historical observation of events, the following passage is a vivid enunciation:-- "It is universally acknowledged, that there is a great uniformity among the actions of men, in all nations and ages, and that human nature remains still the same in its principles and operations. The same motives always produce the same actions; the same events follow from the same causes. Ambition, avarice, self-love, vanity, friendship, generosity, public spirit; these passions, mixed in various degrees, and distributed through society, have been, from the beginning of the world, and still are, the source of all the actions and enterprises which have ever been observed among mankind. Would you know the sentiments, inclinations, and course of life of the Greeks and Romans? study well the temper and actions of the French and English: you cannot be much mistaken in transferring to the former _most_ of the observations which you have made with regard to the latter. Mankind are so much the same, in all times and places, that history informs us of nothing new or strange in this particular. Its chief use is only to discover the constant and universal principles of human nature, by showing men in all varieties of circumstances and situations, and furnishing us with materials from which we may form our observations, and become acquainted with the regular springs of human action and behaviour. These records of wars, intrigues, factions, and revolutions, are so many collections of experiments, by which the politician or moral philosopher fixes the principles of his science, in the same manner as the physician or natural philosopher becomes acquainted with the nature of plants, minerals, and other external objects, by the experiments which he forms concerning them. Nor are the earth, water, and other elements, examined