The rules of justice may be compared to the rules of grammar; the rules of the other virtues to the rules which critics lay down for the attainment of what is sublime and elegant in composition. The one, are precise, accurate, and indispensable. The other, are loose, vague, and indeterminate, and 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. A man may learn to write grammatically by rule, with the most absolute infallibility; and so, perhaps, he may be taught to act justly. But there are no rules whose observance will infallibly lead us to the attainment of elegance or sublimity in writing, though there are some which may help us, in some measure, to correct and ascertain the vague ideas which we might otherwise have entertained of those perfections: and there are no rules by the knowledge of which we can infallibly be taught to act upon all occasions with prudence, with just magnanimity, or proper beneficence. Though there are some which may enable us to correct and ascertain in several respects, the imperfect ideas which we might otherwise have entertained of those virtues. It may sometimes happen, that with the most serious and earnest desire of acting so as to deserve approbation, we may mistake the proper rules of conduct, and thus be misled by that very principle which ought to direct us. It is in vain to expect, that in this case mankind should entirely approve of our behaviour. They cannot enter into that absurd idea of duty which influenced us, nor go along with any of the actions which follow from it. There is still, however, something respectable in the character and behaviour of one who is thus betrayed into vice, by a wrong sense of duty, or by what is called an erroneous conscience. How fatally soever he may be misled by it, he is still, with the generous and humane, more the object of commiseration than of hatred or resentment. They lament the weakness of human nature, which exposes us to such unhappy delusions, even while we are most sincerely labouring after perfection, and endeavouring to act according to the best principle which can possibly direct us. False notions of religion are almost the only causes which can occasion any very gross perversion of our natural sentiments in this way; and that principle which gives the greatest authority to the rules of duty, is alone capable of distorting our ideas of them in any considerable degree. In all other cases common sense is sufficient to direct us, if not to the most exquisite propriety of conduct, yet to something which is not very far from it; and provided we are in earnest desirous to do well, our behaviour will always, upon the whole, be praise-worthy. That to obey the will of the Deity, is the first rule of duty, all men are agreed. But concerning the particular commandments which that will may impose upon us, they differ widely from one another.