The same observation may be applied to the other powers and faculties of our nature. Their existence and use are the principal objects of our study. Thinking and reasoning, we say, are the operations of some faculty; but in what manner the faculties of thought or reason remain, when they are not exerted, or by what difference in the frame they are unequal in different persons, are questions which we cannot resolve. Their operations alone discover them; when unapplied, they lie hid even from the person to whom they pertain; and their action is so much a part of their nature, that the faculty itself, in many cases, is scarcely to be distinguished from a habit acquired in its frequent exertion. Persons who are occupied with different subjects, who act in different scenes, generally appear to have different talents, or at least to have the same faculties variously formed, and suited to different purposes. The peculiar genius of nations, as well as of individuals, may in this manner arise from the state of their fortunes. And it is proper that we endeavour to find some rule, by which to judge of what is admirable in the capacities of men, or fortunate in the application of their faculties, before we venture to pass a judgment on this branch of their merits, or pretend to measure the degree of respect they may claim by their different attainments. To receive the informations of sense, is perhaps the earliest function of an animal combined with an intellectual nature; and one great accomplishment of the living agent consists in the force and sensibility of his animal organs. The pleasures or pains to which he is exposed from this quarter, constitute to him an important difference between the objects which are thus brought to his knowledge; and it concerns him to distinguish well, before he commits himself to the direction of appetite. He must scrutinize the objects of one sense, by the perceptions of another; examine with the eye, before he ventures to touch; and employ every means of observation, before he gratifies the appetites of thirst and of hunger. A discernment acquired by experience, becomes a faculty of his mind; and the inferences of thought are sometimes not to be distinguished from the perceptions of sense.