3. As nature wisely separates nations which the will of each state, sanctioned even by the principles of international law, would gladly unite under its own sway by stratagem or force; in the same way, on the other hand, she unites nations whom the principle of a cosmopolitan right would not have secured against violence and war. And this union she brings about through an appeal to their mutual interests. The commercial spirit cannot co-exist with war, and sooner or later it takes possession of every nation. For, of all the forces which lie at the command of a state, the power of money is probably the most reliable. Hence states find themselves compelled—not, it is true, exactly from motives of morality—to further the noble end of peace and to avert war, by means of mediation, wherever it threatens to break out, just as if they had made a permanent league for this purpose. For great alliances with a view to war can, from the nature of things, only very rarely occur, and still more seldom succeed. In this way nature guarantees the coming of perpetual peace, through the natural course of human propensities: not indeed with sufficient certainty to enable us to prophesy the future of this ideal theoretically, but yet clearly enough for practical purposes. And thus this guarantee of nature makes it a duty that we should labour for this end, an end which is no mere chimera. SECOND SUPPLEMENT A SECRET ARTICLE FOR PERPETUAL PEACE A secret article in negotiations concerning public right is, when looked at objectively or with regard to the meaning of the term, a contradiction. When we view it, however, from the subjective standpoint, with regard to the character and condition of the person who dictates it, we see that it might quite well involve some private consideration, so that he would regard it as hazardous to his dignity to acknowledge such an article as originating from him. The only article of this kind is contained in the following proposition:—“The opinions of philosophers, with regard to the conditions of the possibility of a public peace, shall be taken into consideration by states armed for war.”