When Plato announces that ethics are something supra-natural and puzzling, his world-view provides him with a basic principle of the ethical which corresponds to these qualities, and also has a definite content. He is in a position to define ethics as a process of becoming pure and free from the world of sense. This, his own special ethic, he develops in the passages where he is consistent with himself. Then, when he cannot complete his argument without an active ethic, he has recourse to the popular theory of virtue. Kant, however, as a child of the modern spirit, cannot let world- and life-denial rank as an ethic. Therefore, since he can go only a part of the way with Plato, he sees himself faced with the confusing task of letting a purposive, activist ethic which is directed on the empirical world originate in impulses which are not determined by any adaptation to the empirical. [pg 108] He can find no solution of the problem thus set. In the form which he gives it it is in fact insoluble. But he never even realises that he has arrived at the problem of finding a basic principle of the moral which is a necessity of thought. He is content with formally characterizing ethical duty as absolutely binding. That duty, unless a real content is at once given to it, remains an empty concept, he is unwilling to admit. For the exalted character of his basic principle of the moral he pays the price of having it devoid of all content. Beginnings of an attempt to establish a basic moral principle which has a content are to be found in his treatise, _Prolegomena to a Metaphysic of Morals_ (1785), and again later in _A Metaphysic of Morals_ (1797). In the 1785 volume he arrives at the dictum: “Act in such a way that you use every human being both in your own person and in everyone else’s always as an end, never merely as a means.” But instead of seeing how far the totality of ethical duties can be developed out of this principle, he prefers in the 1797 treatise to set before ethics two ends to be aimed at, viz. the perfecting of oneself and the happiness of others, and to enlarge upon the virtues which promote them. In his investigation of the ethic which aims at personal perfecting, he drives his gallery with sure instinct towards the recognition that all virtues which contribute thereto must be conceived of as manifestations of sincerity and of reverence for one’s own spiritual being. He does not, however, go the length of comprehending these two as a unity, just as little does he concern himself to make clear the inner connexion between self-perfecting and effort directed to the common good, and in that way to dig down to the roots of the ethical as such.