But how destructive soever this system may appear, it could never have imposed upon so great a number of persons, nor have occasioned so general an alarm among those who are the friends of better principles, had it not in some respects bordered upon the truth. A system of natural philosophy may appear very plausible, and be for a long time very generally received in the world, and yet have no foundation in nature, nor any sort of resemblance to the truth. The vortices of Des Cartes were regarded by a very ingenious nation, for near a century together, as a most satisfactory account of the revolutions of the heavenly bodies. Yet it has been demonstrated, to the conviction of all mankind, that these pretended causes of those wonderful effects, not only do not actually exist, but are utterly impossible, and if they did exist, could produce no such effects as are ascribed to them. But it is otherwise with systems of moral philosophy, and an author who pretends to account for the origin of our moral sentiments, cannot deceive us so grossly, nor depart so very far from all resemblance to the truth. When a traveller gives an account of some distant country, he may impose upon our credulity the most groundless and absurd fictions as the most certain matters of fact. But when a person pretends to inform us of what passes in our neighbourhood, and of the affairs of the very parish which we live in, though here too, if we are so careless as not to examine things with our own eyes, he may deceive us in many respects, yet the greatest falsehoods which he imposes upon us must bear some resemblance to the truth, and must even have a considerable mixture of truth in them. An author who treats of natural philosophy, and pretends to assign the causes of the great phenomena of the universe, pretends to give an account of the affairs of a very distant country, concerning which he may tell us what he pleases, and as long as his narration keeps within the bounds of seeming possibility, he need not despair of gaining our belief. But when he proposes to explain the origin of our desires and affections, of our sentiments of approbation and disapprobation, he pretends to give an account, not only of the affairs of the very parish that we live in, but of our own domestic concerns. Though here too, like indolent masters who put their trust in a steward who deceives them, we are very liable to be imposed upon, yet we are incapable of passing any account which does not preserve some little regard to the truth. Some of the articles, at least, must be just, and even those which are most overcharged must have had some foundation, otherwise the fraud would be detected even by that careless inspection which we are disposed to give. The author who should assign, as the cause of any natural sentiment, some principle which neither had any connexion with it, nor resembled any other principle which had some such connexion, would appear absurd