one of the younger sons of Landgrave Maurice of HesseCassel, the political associate of the French King Henry IV and of Geneva, whose edifice of a Protestant polity, constructed with infinite trouble, had been ruthlessly swept away early in the Thirty Years War, and whose dynasty was only by the most careful steering brought safe out of the waves of that ruinous conflict. After its close Landgrave Ernest, although he had gallantly come forward to offer the services of his sword to the Emperor against the Turks, soon gave himself up to his endeavours to keep up a petty principality of his own on the Rhine, and to have his own way in it. He had become a convert to the Church of Rome, and being anxious to induce others to follow his example, carried on his propaganda by all the means in his power, publishing a treatise called The Discreet Catholic, and, with less discretion than might have been expected from its author, establishing at Rheinfels a sort of college for ladies of whom several were converts like himself, and for whom, in spite of his sceptical kinsfolk, he cherished a platonic interest. He made no secret to Leibniz of his wish that, as they shared in many common interests, so they might be united in the same church; but, since this could not be, he was content to discuss projects of Reunion, though he thought that Pietists and Chiliasts and other visionaries, as he called them (including no less a name than that of Spener in his denunciation), must be looked upon as obstacles in the path.
The toleration which is, in some measure at least, the product of indifference, and the intolerance which springs from impatience of all private judgment but one's own—neither of these was an ally on whom Leibniz could greatly depend in his long-sustained effort to assert as the basis of reunion the existing inner unity of the Christian Church at large. For this, the in essentialibus unitas of St. Augustine, was the principle which he continued to press in both the chief phases of the movement in which he bore a part. The more hopeful
