The questions relating to marriage are wholly undecideable by intuition. The natural impulses are for unlimited co-habitation. The degree of restraint to be put upon this tendency is not indicated by any sentiment that can be discovered in the mind. The case is very peculiar. In thefts and murder, the immediate consequences are injury to some one; in sexual indulgence, the immediate result is agreeable to all concerned. The evils are traceable only in remote consequences, which intuition can know nothing of. It is not to be wondered, therefore, that nations, even highly civilized, have differed widely in their marriage institutions; agreeing only in the propriety of adopting and enforcing _some_ regulations. So essentially has this matter been bound up with the moral code of every society, that a proposed criterion of morality unable to grapple with it, would be discarded as worthless. Yet there is no intuitive sentiment that can be of any avail in the question of marriage with a deceased wife's sister. 9. Fifthly, It is practicable to analyze or resolve the Moral Faculty; and, in so doing, to explain, both its peculiar property, and the similarity of moral judgments so far as existing among men. We begin, by estimating the operation of (1) Prudence. (2) Sympathy, and (3) the Emotions generally. The inducements to perform a moral act, as, for example, the fulfilling of a bargain,--are plainly seen to be of various kinds. (1) Prudence, or Self-interest, has obviously much to do with the moral conduct. Postponing for the present the consideration of Punishment, which is one mode of appeal to the prudential regards, we can trace the workings of self-interest on many occasions wherein men act right. To fulfil a bargain is, in the great majority of cases, for the advantage of the agent; if he fails to perform his part, others may do the same to him. Our self-interest may look still farther. We may readily discover that if we set an example of injustice, it may be taken up and repeated to such a degree that we can count upon nothing; social security comes to an end, and individual existence, even if possible, would cease to be desirable. A yet higher view of self-interest informs us, that by performing all our obligations to our fellows, we not only attain reciprocal performance, but generate mutual affections and sympathies, which greatly augment the happiness of life. (2) Sympathy, or Fellow-feeling, the source of our disinterested actions, must next be taken into the account. It is a consequence of our sympathetic endowment that we revolt from inflicting pain on another, and even forego a certain satisfaction to self rather than be the occasion of suffering to a fellow creature. Moved thus, we perform many obligations on the ground of the misery (not our own) accruing from their neglect.