For the last three centuries, the most discussed point in English ethical literature (save perhaps whether moral knowledge is intuitive or derived from experience) has been the relation of regard for one's own self and for other selves as motives of action--"the crux of all ethical speculation," Spencer terms it. All views have been represented: (a) that man naturally acts from purely selfish motives and that morality consists in an enforced subjection of self-love to the laws of a common social order, (b) That man is naturally selfish, while morality is an "enlightened selfishness," or a regard for self based upon recognition of the extent to which its happiness requires consideration of others. (c) That the tendencies of the agent are naturally selfish, but that morality is the subjection of these tendencies to the law of duty. (d) That man's interests are naturally partly egoistic and partly sympathetic, while morality is a compromise or adjustment of these tendencies. (e) That man's interests are naturally both, and morality a subjection of both to conscience as umpire. (f) That they are both, while morality is a subjection of egoistic to benevolent sentiments. (g) That the individual's interests are naturally in objective ends which primarily are neither egoistic nor altruistic; and these ends become either selfish or benevolent at special crises, at which times morality consists in referring them, equally and impartially for judgment, to a situation in which the interests of the self and of others concerned are involved: _to a common good_. =Three Underlying Psychological Principles.=--We shall make no attempt to discuss these various views in detail; but will bring into relief some of the factors in the discussion which substantiate the view (g) stated last. It will be noted that the theories rank themselves under three heads with reference to the constitution of man's tendencies: holding they (1) naturally have in view personal ends exclusively or all fall under the principle of self-love or self-regard; that (2) some of them contemplate one's own happiness and some of them that of others; that (3) primarily they are not _consciously_ concerned with either one's own happiness or that of others. Memory and reflection may show (just as it shows other things) that their consequences affect both the self and others, when the recognition of this fact becomes an additional element, either for good or for evil, in the motivation of the act. We shall consider, first, the various senses in which action occurs, or is said to occur, in behalf of the person's own self; and then take up, in similar fashion, its reference to the interests of others.