To characterize the sentiment of the heart, upon which each particular virtue is founded, though it requires both a delicate and an accurate pencil, is a task, however, which may be executed with some degree of exactness. It is impossible, indeed, to express all the variations which each sentiment either does or ought to undergo, according to every possible variation of circumstances. They are endless, and language wants names to mark them by. The sentiment of friendship, for example, which we feel for an old man is different from that which we feel for a young: that which we entertain for an austere man different from that which we feel for one of softer and gentler manners: and that again from what we feel for one of gay vivacity and spirit. The friendship which we conceive for a man is different from that with which a woman affects us, even where there is no mixture of any grosser passion. What author could enumerate and ascertain these and all the other infinite varieties which this sentiment is capable of undergoing? But still the general sentiment of friendship and familiar attachment which is common to them all, may be ascertained with a sufficient degree of accuracy. The picture which is drawn of it, though it will always be in many respects incomplete, may, however, have such a resemblance as to make us know the original when we meet with it, and even distinguish it from other sentiments to which it has a considerable resemblance, such as goodwill, respect, admiration.
To describe, in a general manner, what is the ordinary way of acting to which each virtue would prompt us, is still more easy. It is, indeed, scarce possible to describe the internal sentiment or emotion upon which it is founded, without doing something of this kind. It is impossible by language to express, if I may say so, the invisible features of all the different modifications of passion as they show themselves within. There is no other way of marking and distinguishing them from one another, but by describing the effects which they produce without, the alterations which they occasion in the countenance, in the air and external behaviour, the resolutions they suggest, the actions they prompt to. It is thus that Cicero, in the first book of his Offices, endeavours to direct us to the practice of the four cardinal virtues, and that Aristotle in the practical parts of his Ethics, points out to us the different habits by which he would have us regulate our behaviour, such as liberality, magnificence, magnanimity, and even jocularity and good humour, qualities which that indulgent philosopher has thought worthy of a place in the catalogue of the virtues, though the lightness of that approbation which we naturally bestow upon them, should not seem to entitle them to so venerable a name.
Such works present us with agreeable and lively pictures of manners. By the vivacity of their descriptions they inflame our natural love of virtue, and increase our abhorrence of vice: by the justness as well as delicacy of their observations they may often help both to correct and to ascertain our natural sentiments with regard to the propriety of conduct, and suggesting many nice and delicate attentions, form us to a more exact justness of behaviour, than what, without such instruction, we should have been apt to think of. In treating of the rules of morality, in this manner, consists the science which is properly called Ethics, a science which, though like criticism, it does not admit of the most accurate precision, is, however, both highly useful and agreeable. It is of all others the most susceptible of the embellishments of eloquence, and by means of them of bestowing, if that be possible, a new importance upon the smallest rules of duty. Its precepts, when thus dressed and adorned, are capable of producing upon the flexibility of youth, the noblest and most lasting impressions, and as they fall in with the natural magnanimity of that generous age, they are able to inspire, for a time at least, the most heroic resolutions, and thus tend both to establish and confirm the best and most useful habits of which the mind of man is susceptible. Whatever precept and exhortation can do to animate us to the practice of virtue, is done by this science delivered in this manner.
II. The second set of moralists, among whom we may count all the casuists of the middle and latter ages of the Christian church, as well as all those who in this and in the preceding century have treated of what is called natural jurisprudence, do not content themselves with characterizing in this general manner that tenor of conduct which they would recommend to us, but endeavour to lay down exact and precise rules for the direction of every circumstance of our behaviour. As justice is the only virtue with regard to which such exact rules can properly be given; it is this virtue, that has chiefly fallen under the consideration of those two different sets of writers. They treat of it, however, in a very different manner.
Those who write upon the principles of jurisprudence, consider only what the person to whom the obligation is due, ought to think himself entitled to exact by force; what every impartial spectator would approve of him for exacting, or what a judge or arbiter, to whom he had submitted his case, and who had undertaken to do him justice, ought to oblige the other person to suffer or to perform. The casuists, on the other hand, do not so much examine what it is, that might properly be exacted by force, as what it is, that the person who owes the obligation ought to think himself bound to perform from the most sacred and scrupulous regard to the general rules of justice,
