It was observed in the third part of this discourse, that the rules of justice are the only rules of morality which are precise and accurate; that those of all the other virtues are loose, vague, and indeterminate; that the first may be compared to the rules of grammar; the others to those which critics lay down for the attainment of what is sublime and elegant in composition, and which present us rather with a general idea of the perfection we ought to aim at, than afford us any certain and infallible directions for acquiring it. As the different rules of morality admit such different degrees of accuracy, those authors who have endeavoured to collect and digest them into systems have done it in two different manners; and one set has followed thro’ the whole that loose method to which they were naturally directed by the consideration of one species of virtues; while another has as universally endeavoured to introduce into their precepts that sort of accuracy of which only some of them are susceptible. The first have wrote like critics, the second like grammarians. I. The first, among whom we may count all the ancient moralists, have contented themselves with describing in a general manner the different vices and virtues, and with pointing out the deformity and misery of the one disposition as well as the propriety and happiness of the other, but have not affected to lay down many precise rules that are to hold good unexceptionably in all particular cases. They have only endeavoured to ascertain, as far as language is capable of ascertaining, first, wherein consists the sentiment of the heart, upon which each particular virtue is founded, what sort of internal feeling or emotion it is which constitutes the essence of friendship, of humanity, of generosity, of justice, of magnanimity, and of all the other virtues, as well as of the vices which are opposed to them: and, secondly, What is the general way of acting, the ordinary tone and tenour of conduct to which each of those sentiments would direct us, or how it is that a friendly, a generous, a brave, a just, and a humane man, would, upon ordinary occasions, chuse to act.