In France some attempts were made by Cardinal Richelieu to bring about a reunion between the Catholics and the Calvinists. In taking these steps he was influenced more by considerations of state than by zeal for the welfare of the Church, but the gulf separating the two parties was too wide to be bridged over even by French patriotism. In Poland, where unity was particularly required and where the disastrous consequences of religious strife were only too apparent, Ladislaus V. determined to summon a conference at Thorn in 1645 to discuss the religious differences, but though it was attended by representatives from several states of Germany it produced no good results. In Germany the work, that had proved too great for the theologians, was undertaken by the princes in 1644, with no better results. Later on, at the instigation of the Emperor, Christopher Royas de Spinola, an Austrian bishop, spent the last twenty years of his life (1675- 1695) in a vain effort to put an end to the religious dispute. Heedless of repeated rebuffs, he passed from court to court in Germany till at last at Hanover he saw some prospect of success. Duke Ernest August assembled a conference of Lutheran theologians (1679), the principal of whom was Molanus, a Protestant abbot of Loccum. The Lutheran theologians were willing to agree that all Christians should return immediately to their obedience to the Pope, on condition, however, that the decrees of the Council of Trent should be suspended, and that a new General Council composed of representatives of all parties should be assembled to discuss the principal points in dispute. On his side Royas was inclined to yield a good deal in regard to clerical celibacy and the authority of secular princes in ecclesiastical affairs. Innocent XI., while not approving of what had been done, praised the bishop for the efforts he had made to bring about a reunion. Leibniz, the librarian and archivist of the Duke of Brunswick, having taken already some part in the work of bringing about a reconciliation, entered into a correspondence with Bossuet, the Bishop of Meaux. He favoured a compromise on the basis of acceptance of the beliefs of the first five centuries, and published his /Systema Theologicum/ as a means of bringing the Catholic standpoint before the minds of his co-religionists. Bossuet and the French historian Pellisson reciprocated his efforts, but the schemes of Louis XIV. and the hopes of the English succession entertained by the House of Brunswick out an end to all chances of success.