Cicero, in his first book of offices, says we do not talk of the justice of horses or lions. In conformity to which, Plutarch, in the life of Cato the elder, observes, that we are formed by nature to use law and justice towards men only. In addition to the above, Lactantius may be cited, who, in his fifth book, says that in all animals devoid of reason we see a natural bias of self-love. For they hurt others to benefit themselves; because they do not know the evil of doing wilful hurt. But it is not so with man, who, possessing the knowledge of good and evil, refrains, even with inconvenience to himself, from doing hurt. Polybius, relating the manner in which men first entered into society, concludes, that the injuries done to parents or benefactors inevitably provoke the indignation of mankind, giving an additional reason, that as understanding and reflection form the great difference between men and other animals, it is evident they cannot transgress the bounds of that difference like other animals, without exciting universal abhorrence of their conduct. But if ever justice is attributed to brutes, it is done improperly, from some shadow and trace of reason they may possess. But it is not material to the nature of right, whether the actions appointed by the law of nature, such as the care of our offspring, are common to us with other animals or not, or, like the worship of God, are peculiar to man. XII. The existence of the Law of Nature is proved by two kinds of argument, _a priori_, and _a posteriori_, the former a more abstruse, and the latter a more popular method of proof. We are said to reason _a priori_, when we show the agreement or disagreement of any thing with a reasonable and social nature; but _a posteriori_, when without absolute proof, but only upon probability, any thing is inferred to accord with the law of nature, because it is received as such among all, or at least the more civilized nations. For a general effect can only arise from a general cause. Now scarce any other cause can be assigned for so general an opinion, but the common sense, as it is called, of mankind. There is a sentence of Hesiod that has been much praised, that opinions which have prevailed amongst many nations, must have some foundation. Heraclitus, establishing common reason as the best criterion of truth, says, those things are certain which generally appear so. Among other authorities, we may quote Aristotle, who says it is a strong proof in our favour, when all appear to agree with what we say, and Cicero maintains that the consent of all nations in any case is to be admitted for the law of nature. Seneca is of the same opinion, any thing, says he, appearing the same to all men is a proof of its truth. Quintilian says, we hold those things to be true, in which all men agree. We have called them the more civilized nations, and not without reason. For, as Porphyry well observes, some nations are so strange that no fair