Voltaire was forty years of age; Madame, a woman of intellect and varied culture, was twelve years younger. During fifteen years, when he was not wandering abroad, Cirey was the home of Voltaire, and Madame du Chatelet his sympathetic, if sometimes his exacting companion. To this period belong the dramas _Alzire_, _Zulime_, _L'Enfant Prodigue_, _Mahomet_, _Merope_, _Nanine_. The divine Emilie was devoted to science, and Voltaire interpreted the Newtonian philosophy to France or discussed questions of physics. Many admirable pieces of verse--ethical essays in the manner of Pope, lighter poems of occasion, _Le Mondain_, which contrasts the golden age of simplicity with the much more agreeable age of luxury, and many besides--were written. Progress was made with the shameless burlesque on Joan of Arc, _La Pucelle_. In _Zadig_ Voltaire gave the first example of his sparkling tales in prose. Serious historical labours occupied him--afterwards to be published--the _Siecle de Louis XIV._ and the great _Essai sur les Moeurs_. In 1746, with the support of Madame de Pompadour, he entered the French Academy. The death of Madame du Chatelet, in 1749, was a cruel blow to Voltaire. He endeavoured in Paris to find consolation in dramatic efforts, entering into rivalry with the aged Crebillon. Among Voltaire's correspondents, when he dwelt at Cirey, was the Crown Prince of Prussia, a royal _philosophe_ and aspirant French poet. Royal flatteries were not more grateful to Voltaire than philosophic and literary flatteries were to Frederick. Personal acquaintance followed; but Frederick would not receive Madame du Chatelet, and Voltaire would not desert his companion. Now when Madame was dead, when the Pompadour ceased from her favours to the poet, when Louis turned his back in response to a compliment, Frederick was to secure his philosopher. In July 1750 Voltaire was installed at Berlin. For a time that city was "the paradise of _philosophes_."