It will be convenient to discuss our subject under the two heads: I. Of ethics in general; and II. Of sexual ethics in particular. I. ETHICS Ethics is the science of morals. Morals may be said to consist of two very distinct factors, which we will attempt to analyse:―― 1. An instinctive sense, the conscience, sense of duty, or ethical impulse, which says to us: “This shalt thou do, and that shalt thou leave undone.” A person in whom it is highly developed experiences satisfaction if he obeys the “voice of conscience,” and remorse if he fails to do so. 2. The second factor of morals includes the objects of conscience, that is, the things which conscience commands or forbids. The great philosopher Kant founded upon the instinct of conscience his Categorical Imperative, and held the further investigation of its causes to be unnecessary. If the conscience says “Thou shalt,” one must simply act accordingly. This is, in Kant’s opinion, the absolute moral law, which bids or forbids an action independently of any other consideration. The further they progress, however, the more do reason and science rebel against the conception of the Categorical Imperative. Kant, great as he was, was not infallible. The imperative of the conscience is in itself no more categorical and absolute than that of the sexual impulse, of fear, of maternal love, or of other emotions and instincts. In the first place daily observation shows us the existence of people born conscienceless, in whom the sense of duty is lacking, who are aware of no “Thou shalt,” and in whose eyes other individuals are merely welcome objects for plunder or inconvenient hindrances. For these “ethically defective” persons there can be no categorical imperative, because they have no conception of duty. The ethical sense may exist in varying degrees of intensity. In some persons the conscience is weak, in others strong; and there are cases in which it is developed to an exaggerated and morbid extent. People of this type suffer pangs of conscience over the merest trifle, reproach themselves for “sins” which they have never committed, or which are no sins at all, and make themselves and others miserable. How can all this be reconciled with the absolute moral law as stated by Kant? The theory of the Categorical Imperative becomes even more absurd when we consider the actions to which men are guided by their consciences. The same habit――the drinking of wine, for instance――may be for one man a matter of duty (for a Christian at the Eucharist or for an officer at the toast of the King); for another (the Mohammedan) it may be forbidden as a deadly sin. Murder, which is certainly almost universally prohibited by conscience, is a “duty” in time of war, and even for certain persons in the duel. Such instances could be multiplied indefinitely.