[196] In 1868 it was affirmed, in an Act passed by the Congress of the United States, that “the right of expatriation is a natural and inherent right of all people.” I do not know how far this would be taken to imply that a man has a moral right to leave his country whenever he finds it convenient--provided no claims except those of Patriotism retain him there. But if it was intended to imply this, I think the statement would not be accepted in Europe without important limitations: though I cannot state any generally accepted principle from which such limitations could be clearly deduced. [197] How far we are bound to make reparation when the harm is involuntary, and such as could not have been prevented by ordinary care on our part, is not clear: but it will be convenient to defer the consideration of this till the next chapter (§ 5): as the whole of this department of duty is more commonly placed under the head of Justice. [198] I raise this question, because if the rule of ‘living according to Nature’ were really adopted as a first principle, in any ordinary meaning of the term ‘nature,’ it would certainly seem to be the duty of all normal human beings to enter into conjugal relations: but just this instance seems to show that the principle is not accepted by Common Sense. See Book i. chap. vi. § 2. [199] The moral necessity of prohibiting polygamy is sometimes put forward as an immediate inference from the equality of the numbers of the two sexes. This argument, however, seems to require the assumption that all men and women ought to marry: but this scarcely any one will expressly affirm: and actually considerable numbers remain unmarried, and there is no reason to believe that in countries where polygamy is allowed, paucity of supply has ever made it practically difficult for any man to find a mate. [200] Cf. Wayland, _Elements of Moral Science_, Book ii. part ii. class 2, § 2. [201] I use the term here to imply a mutual affection more intense than the kindly feeling which a moral man desires to find towards all persons with whom he is brought into continual social relations, through business or otherwise. [202] It was before observed that this is only one--and not always the most prominent--element of the whole emotional state which we call love. [203] See Book iv. chap. iii. § 3. CHAPTER V JUSTICE § 1. We have seen that in delineating the outline of duty, as intuitively recognised, we have to attempt to give to common terms a definite and precise meaning. This process of definition always requires some reflection and care, and is sometimes one of considerable difficulty. But there is no case where the difficulty is greater, or the result more disputed, than when we try to define Justice.