His first work, which appeared when he was twenty-two years old, was a treatise written under the name of George Vlicorius, recommending the choice of the Elector Palatine to be King of Poland. In 1670 he published his first philosophical work, an edition of ‘Marius Nizolius contra Pseudophilosophos;’ and in the following year two treatises on abstract and concrete motion, severally dedicated to the French Academy and the Royal Society. During his abode at Nuremberg, the Baron de Boinebourg, minister of the Elector of Mayence, procured a legal appointment for him in that state. While he held this post he travelled into France and England. After the death of the Elector, he accepted a similar appointment in the dominions of the Duke of Brunswick-Lunenberg. At the peace of Nimeguen in 1678 he wrote upon some disputed ceremonials, under the title of Cesarinus Furstnerius, and displayed a great extent of reading, and a little of that speculative spirit which afterwards produced the _pre-established harmony_. He is said, though a Lutheran, to have argued on the supposition that Europe was to be considered as a large federation, of which the Emperor was the temporal, and the Pope the spiritual, head. In 1679 he was engaged by the reigning Duke to write the history of the House of Brunswick. On this service he went through Germany and Italy in search of authorities. It is related that, on one occasion, having left Venice in a small boat, a storm arose, and the boatmen began to discuss in Italian, which they supposed their passenger did not understand, the propriety of throwing the heretic overboard. Leibnitz, with great presence of mind, drew out a rosary, which he had about him _par précaution_, as Fontenelle supposes, who does not seem to guess that this anecdote, coupled with what has preceded, makes it at least an even chance that Leibnitz was really a Catholic. And this is negatively supported by the fact, that, Lutheran as he was considered, he very rarely attended the services of his church, in spite of the publicly-expressed disapprobation of the clergy. But on the other hand, he positively refused to profess Catholicism, when an advantageous settlement at Paris was offered on that condition. That he was both a religious man and a Christian is sufficiently attested by his writings. He returned from his tour in 1690, and in 1693 published his ‘Codex Juris Gentium Diplomaticus.’ He had published almost at the same time with his first work a treatise on the study of jurisprudence. The first volume of the ‘History of Brunswick’ appeared in 1707, and two others in 1710 and 1711.