Leibniz was impelled to a compromise with 'popery', not only by the religious divisions of Germany, but (at one stage) by the political weakness of the German Protestant States. At the point of Louis XIV's highest success, the Protestant princes had no hope but in Catholic Austria, and Austria was distracted by Turkish pressure in the rear. Leibniz hoped to relieve the situation by preaching a crusade. Could not the Christian princes sink their differences and unite against the infidel? And could not the Christian alliance be cemented by theological agreement? Hence Leibniz's famous negotiation with Bossuet for a basis of Catholic-Lutheran concord. It was plainly destined to fail; and it was bound to recoil upon its author. How could he be a true Protestant who treated the differences with the Catholics as non-essentials? How could he have touched pitch and taken no defilement? Leibniz was generally admired, but he was not widely trusted. As a mere politician, he may be judged to have over-reached himself. It has been the object of the preceding paragraphs to show that Leibniz[11] the politician and Leibniz the theologian were one and the same person; not at all to suggest that his rational theology was just political expediency. We may apply to him a parody of his own doctrine, the pre-established harmony between nature and grace. Everything happens as though Leibniz were a liberal politician, and his theology expressed his politics. Yes, but equally, everything happens as though Leibniz were a philosophical theologian, and his politics expressed his theology. His appreciation of Catholic speculation was natural and sincere; his dogmatic ancestry is to be looked for in Thomism and Catholic humanism as much as anywhere. Above all, he had himself a liberal and generous mind. It gave him pleasure to appreciate good wherever he could see it, and to discover a soul of truth in every opinion. From the moment when Leibniz became aware of himself as an independent thinker, he was the man of a doctrine. Sometimes he called it 'my principles', sometimes 'the new system', sometimes 'pre-established harmony'. It could be quite briefly expressed; he was always ready to oblige his friends with a summary statement, either in a letter or an enclosed memorandum, and several such have come down to us. The doctrine may have been in Leibniz's view simple, but it was applicable to every department of human speculation or enquiry. It provided a new alphabet of philosophical ideas, and everything in heaven and earth could be expressed in it; not only could be, but ought to be, and Leibniz showed tireless energy in working out restatements of standing problems.