It was not the fault of Madame du Châtelet that the life of Cirey was not the undisturbed type of Voltaire’s existence during the fifteen years of their companionship. Many pages might be filled with a mere list of the movements from place to place to which Voltaire resorted, partly from reasonable fear of the grip of a jealous and watchful government, partly from eagerness to bring the hand of the government upon his enemies, and most of all from the uncontrollable restlessness of his own nature. Amsterdam, the Hague, Brussels, Berlin, the little court of Lunéville, and the great world of Paris, too frequently withdrew him from the solitary castle at Cirey, though he never failed to declare on his return, and with perfect sincerity, that he was never so happy anywhere else. If it was true that the Marquise made her poet’s life a little hard to him, it is impossible to read her correspondence without perceiving that he, too, though for no lack of sensibility and good feeling, often made life extremely hard for her. Besides their moral difference, there was a marked discrepancy in intellectual temperament, which did not fail to lead to outward manifestations. Voltaire was sometimes a little weary of Newton and exact science, while the Marquise was naturally of the rather narrow turn for arid truths which too often distinguishes clever women inadequately disciplined by contact with affairs. She and Voltaire both competed for a prize offered by the Academy for essays on the propagation of fire (1737). Neither of them was successful, for the famous Euler was a competitor. The second and third prizes were given to two obscurer persons, because their essays were Cartesian, that is to say, they were scientifically orthodox. The two philosophers of Cirey also took part, and on different sides, in the obstinate physico-mathematical controversy which Leibnitz had first raised towards the close of the seventeenth century, as to the measure of moving forces[88]. The Marquise, under circumstances of equivocal glory and with much angry buzzing, with which one has now no concern[89], published her analysis of Leibnitz in 1740, and sided with him against Newton and Descartes. In the notice which Voltaire wrote of his friend’s book he gave a marvellously simple and intelligible account of the issue of the special controversy of _vis viva_[90], but he remained Newtonian, and in 1741 presented a paper to the Academy of Sciences, disputing the Leibnitzian view[91].