More important, by its influence upon contemporary thought, was his famous _Letters on the English_--a work designed to inform his countrymen generally of the literature, thought, and political and theological parties of the rival nation, and, more especially, of the discoveries of Newton and Locke. Descartes, at this moment supreme in France, had succeeded to the vacant throne of the so-called Aristotelian Schoolmen. His system, a great advance upon the old, broached some errors in physics, amongst others the theory of “Vortices” to explain the planetary movements. A much more pernicious and reprehensible error was his absurd denial of conscious feeling and intelligence to the lower races, which was admirably exposed by Voltaire in his _Elémens de Newton_ and elsewhere. In England, Newton’s extraordinary discoveries had already made Descartes obsolete, as far as the _savans_ were concerned at least, but the French scientific world still clung, for the most part, to the Cartesian principles. As for Locke, he had overturned the orthodox creed of “innate ideas,” supplying instead sensation and reflection. This advocacy of the new philosophy, added to the success of his tragedies for the theatre, “Drew [says Voltaire in his _Mémoires_] a whole library of pamphlets down upon me, in which they proved I was a bad poet, an atheist, and the son of a peasant. A history of my life was printed in which this genealogy was inserted. An industrious German took care to collect all the tales of that kind which had been crammed into the libel, they had published against me. They imputed adventures to me with persons I never knew, and with others who never existed. I have found while writing this a letter from the Maréchal de Richelieu which informed me of an impudent lampoon where it was proved his wife had given me an elegant couch, with something else, at a time when he had no wife. At first I took some pleasure in making collections of these calumnies, but they multiplied to such a degree I was obliged to leave off. Such are the fruits I gathered from my labours. I, however, easily consoled myself, sometimes in my retreat at Cirey, and at other times in mixing with the best society.” Amongst other subjects the _Lettres_ (a masterpiece of criticism and sort of essays, since often imitated but seldom or never, perhaps, equalled in their kind) contains an admirable essay upon the Quakers, to whom he did justice. He introduces one of them in conversation with him, thus apologising for his _eccentricities_: