In 1641, appeared his Meditations De Primâ Philosophiâ, on the Soul, on Freewill, and on the Existence of a Creator. Various parts of this treatise were criticised by Hobbes, Gassendi, and some others; but so much was the reputation of Des Cartes increased in France, that the exertions of Mersenne, made by the desire of the author, could not obtain more than one opponent to this work out of all the Sorbonne. This was the afterwards celebrated Arnaud, between whom and Des Cartes a friendly controversy was maintained. But in Holland, the active enmity of Voet, the rector of the university of Utrecht, and others, raised a clamour against Regius, who publicly taught Cartesian doctrines at Utrecht. Des Cartes himself, averse to controversy, wrote strongly to his pupil not to deny or reject any thing commonly admitted, but merely to assert that it was not necessary to the proper conception of the doctrine taught. But Voet, not content with writing books, instituted an unworthy course of clandestine persecution against Des Cartes, by which, in 1642, he obtained the condemnation of the ‘Meditations’ by the magistracy of Utrecht, and gave the author some personal trouble and anxiety. On the other hand, the new philosophy at this time made great progress among the Jesuits, its former opponents. In the middle of the year Des Cartes returned to France, and superintended a new edition of his Principles of Philosophy. But in the following year he went again to Holland, where some decisions in his favour, in matters of alleged libel, the too virulent enmity of Voet, the public teaching of Cartesian doctrines at Leyden by Heereboord, and other things of the same kind, made his reputation gain ground rapidly. About 1647, we find him clear of violent opposition, and actively engaged in the dissemination of various opinions by personal correspondence. He returned again to France, where a pension of 3000 livres was obtained for him: but he is said never to have received any part of it. He came back to Holland, but next year was recalled to France by the promise of another pension, which turned out to be fallacious. He once more returned to Holland, which he left the same year, to fix his residence in Sweden, at the desire of the queen Christina, with whom he had been some time in correspondence. He arrived at Stockholm in September, and while engaged in projecting an Academy of Sciences, at the desire of the queen, was seized with an inflammation of the lungs, which carried him off, February 11, 1650, at the age of 54. His body, seventeen years after, was removed to the church of St. Geneviève at Paris.