rights of all is maintained even when the rights themselves are very unequal, as in slavery and in the system of ranks or castes. There are the greatest differences as to what is equality in the distribution of the produce of labour; some thinking that all should receive alike; others that the neediest should receive most; others that the distribution should be according to labour or services. To get a clue to the common idea running through all these meanings, the author refers to the etymology of the word, which, in most languages, points to something ordained by _law_. Even although there be many things considered just, that we do not usually enforce by law, yet in these cases it would give us pleasure if law could be brought to bear upon offenders. When we think a person bound in justice to do a thing, we should like to see him punished for not doing it; we lament the obstacles that may be in the way, and strive to make amends by a strong expression of our own opinion. The idea of legal constraint is thus the generating idea of justice throughout all its transformations. The real turning point between morality and simple expediency is contained in the penal sanction. Duty is what we may _exact_ of a person; there may be reasons why we do not exact it, but the person himself would not be entitled to complain if we did so. Expediency, on the other hand, points to things that we may wish people to do, may praise them for doing, and despise them for not doing, while we do not consider it proper to bring in the aid of punishment. There enters farther into the idea of Justice what has been expressed by the ill-chosen phrase, 'perfect obligation,' meaning that the duty involves a moral right on the part of some definite person, as in the case of a debt; an imperfect obligation is exemplified by charity, which gives no legal claim to any one recipient. Every such right is a case of Justice, and not of Beneficence. The Idea of Justice is thus shown to be grounded in Law; and the next question is, does the strong feeling or sentiment of Justice grow out of considerations of utility? Mr. Mill conceives that though the notion of expediency or utility does not give birth to the sentiment, it gives birth to what is _moral_ in it.