That it is possible to reduce even this restricted part to scientific definiteness, can scarcely be said. But ethical requirements may here be to such extent affiliated upon physical necessities, as to give them a partially scientific authority. It is clear that between the expenditure of bodily substance in vital activities, and the taking in of materials from which this substance may be renewed, there is a direct relation. It is clear, too, that there is a direct relation between the wasting of tissue by effort, and the need for those cessations of effort during which repair may overtake waste. Nor is it less clear that between the rate of mortality and the rate of multiplication in any society, there is a relation such that the last must reach a certain level before it can balance the first, and prevent disappearance of the society. And it may be inferred that pursuits of other leading ends are, in like manner, determined by certain natural necessities, and from these derive their ethical sanctions. That it will ever be practicable to lay down precise rules for private conduct in conformity with such requirements, may be doubted. But the function of Absolute Ethics in relation to private conduct will have been discharged when it has produced the warrant for its requirements as generally expressed; when it has shown the imperativeness of obedience to them; and when it has thus taught the need for deliberately considering whether the conduct fulfills them as well may be. Under the ethics of personal considered in relation to existing conditions, have to come all questions concerning the degree in which immediate personal welfare has to be postponed, either to ultimate personal welfare or to the welfare of others. As now carried on, life hourly sets the claims of present self against the claims of future self, and hourly brings individual interests face to face with the interests of other individuals, taken singly or as associated. In many of such cases the decisions can be nothing more than compromises; and ethical science, here necessarily empirical, can do no more than aid in making compromises that are the least objectionable. To arrive at the best compromise in any case, implies correct conceptions of the alternative results of this or that course. And, consequently in so far as the absolute ethics of individual conduct can be made definite, it must help us to decide between conflicting personal requirements, and also between the needs for asserting self and the needs for subordinating self. § 109. From that division of Ethics which deals with the right regulation of private conduct, considered apart from the effects directly produced on others, we pass now to that division of Ethics which, considering exclusively the effects of conduct on others, treats of the right regulation of it with a view to such effects.