Another significant writing of this period is Penn's "Plan for the Peace of Europe." The calamities of the war then in progress on the Continent gave him arguments enough for the desirableness of peace. The means of peace is justice, and the means of justice is government. It is plain to all that a state wherein any private citizen might avenge himself upon his neighbor would be a place of confusion and distress. "For this cause they have sessions, terms, assizes, and parliaments, to overrule men's passions and resentments, that they may not be judges in their own cause, nor punishers of their own wrongs." Penn proposes that the same relation between peace and justice which is enforced between citizen and citizen be also enforced between nation and nation. "Now," he says, "if the sovereign princes of Europe ... for love of peace and order [would] agree to meet by their stated deputies in a general Diet, Estates or Parliament and there establish rules of justice for sovereign princes to observe one to another; and thus to meet yearly, or once in two or three years at the farthest, or as they shall see cause, and to be stiled, The Sovereign or Imperial Diet, Parliament or State of Europe: before which Sovereign Assembly should be brought all differences depending between one sovereign and another that cannot be made up by private embassies before the sessions begin; and that if any of the sovereignties that constitute these imperial states shall refuse to submit their claim or pretensions to them, or to abide and perform the judgment thereof and seek their remedy by arms, or delay their compliance beyond the time prefixt in their resolutions, all the other sovereignties, united as one strength, shall compel the submission and performance of the sentence, with damages to the suffering party, and charges to the sovereignties that obliged their submission; ... peace would be procured and continued in Europe." The principle of international arbitration, the Conference at the Hague, and all like meetings which shall be held hereafter, are thus foreshadowed. These two productions of Penn's season of retirement--the "Fruits of Solitude," and the "Plan for the Peace of Europe"--illustrate again the two qualities which make him singularly eminent among the founders of commonwealths. He was at once a philosopher and a statesman; he was interested alike in religion and in politics. There have been many politicians to whom religion has been of no concern. There have been many religious persons in high positions who have been so shut in by church walls that they have been incapable of a wider outlook; they have accordingly been narrow, prejudiced, and often unpractical people; they have been blind to the elemental social fact of difference; they have hated the thought of toleration. Penn was almost alone among the good men of our era of colonization in being at the same time a man of the world and a man of the other world.