Clairaut joined his good friend Maupertuis’ year-long expedition to Lapland to determine the Earth’s true shape, though later the two fell out. A friend of Voltaire and Châtelet, he helped Châtelet translate Newton into French. Visiting Bernoulli with Maupertuis, he befriended König and started collaborating with him. Maclaurin was among Clairaut’s mathematical correspondents. Euler – who corresponded for 24 years – wrote in support of his lunar orbital calculations. A former prodigy himself, Clairaut praised the 16-year-old Condorcet’s mathematical abilities.