Two tasks of Scientific Ethics, as Historical Ethics and as Philosophical Ethics, are to be distinguished. Historical Ethics has to do with the description and explanation of the development of Positive Morality. Philosophical Ethics has to decide upon the worth of the various forms assumed by the latter. Philosophical Ethics is a practical science, and is based upon the supposition that we set ourselves ends which may be reached through human action. Every ethical judgment presupposes such an end, for feeling is set in motion by the sight or the thought of an act only when the latter promotes, or stands in the way of something, the existence and success of which are desired by us. Not all that is developed as practical morality can be pronounced good. On the other hand, customs which were at first assumed from motives which must be condemned by Philosophical Ethics, may yet prove themselves good, and may be practised, later, from higher motives; and such customs cannot then be condemned on account of their origin. Hence, Philosophical Ethics is both conservative and radical; it respects nothing simply because it exists; but since it endeavors to furnish guidance beyond present standards, it attempts to show how that which has been developed historically may be given new forms and thus used for further progress. It is difficult, from a broader view, to distinguish perfectly between Historical and Philosophical Ethics; the historian has an ideal which he applies more or less in his researches; and the philosopher in Ethics is more or less ruled by the prevailing opinions of his time. This necessitates a continual re-discussion of problems. Yet it does not prevent the existence, in any system, of lasting principles among the less enduring ones.