About this period, frequenting less the fashionable and trifling society of the capital, and contenting himself with the company of a few congenial minds, he formed amongst others a sympathetic friendship with the Marquise de Châtelet, a lady of extraordinary talents. “I was tired [thus he begins his unfinished _Mémoires_], I was tired of the lazy and noisy life led at Paris, of the multitude of _petit-maîtres_, of bad books printed with the approbation of censors and the privilege of the king, of the cabals and parties among the learned, and of the mean arts of plagiarism and book-making which dishonour Literature.” The lady was the equal of Madame Dacier in knowledge of the Greek and Latin languages, and she was familiar with all the best modern writers. She wrote a commentary on Leibnitz. She also translated the _Principia_. Her favourite pursuits, however, were mathematics and metaphysics. “She was none the less fond of the world and those amusements familiar to her age and sex. She determined to leave them all and bury herself in an old ruinous château on the borders of Champagne and Lorraine, situated in a barren and unhealthy soil. This old château she ornamented with sufficiently pretty gardens. I built a gallery, and formed a very good collection of natural history, added to which we had a library not badly furnished. We were visited by several of the _savans_, who came to philosophise in our retreat.... I taught English to Madame de Châtelet, who, in about three months understood it as well as I did, and read Newton, and Locke, and Pope, with equal ease. We read all the works of Tasso and Ariosto together, so that when Algerotti came to Cirey, where he finished his _Newtonianism for Women_, he found her sufficiently skilful in his own language to give him some very excellent information by which he profited.” Voltaire had already (1741) given to the world his _Elémens de Newton_--a work which, in conjunction with other parts of his writings, proves that had he chosen to apply himself wholly to natural philosophy or to mathematics he might have reached the highest fame in those departments of science. It is in the _Elémens_ that Voltaire records his noble protest at the same time against the monstrous hypothesis of Descartes, to which we have already referred, and against the selfish cruelty of our species. “There is in man a disposition to compassion as generally diffused as his other instincts. Newton had _cultivated_ this sentiment of humanity, and he extended it to the lower animals. With Locke he was strongly convinced that God has given to them a proportion of ideas, and the same feelings which he has to us. He could not believe that God, who has made nothing in vain, would have given to them organs of feeling _in order that they might have no feeling_.