Le Sage in the sciences. Nevertheless, Le Sage later claimed that his father never told him that Fatio had created a theory of gravitation essentially identical to his own. (Le Sage also admitted that he had a pathologically bad memory, so it is unclear if his recollection is accurate.) In any case, Le Sage stated that he knew nothing of Fatio's theory until he was informed by his teacher Gabriel Cramer in 1749. A few years after Fatio's death (which occurred in 1753), Le Sage began trying to acquire Fatio's papers to – according to his own words – rescue them from oblivion, and also for a treatise he planned to write on the history of theories of gravitation. One of Fatio's papers was sent to Le Sage by Abauzit in 1758, and other papers were acquired by Le Sage in 1766, 1770 and 1785. He also started a biographical note on Fatio, although he did not complete it, and he tried without success to publish some of Fatio's papers. The Geneva manuscripts were deposited in the library of Geneva by Prévost after Le Sage's death and are still there. Le Sage wrote to Lambert in 1768: "Nicolas Fatio de Duillier had created a theory in 1689, which is so similar to mine, that it only differed in the elasticity, which he has given his intensely agitated matter". There he outlined the great similarity of the theories, but incorrectly claimed that Fatio assumed elastic collisions, even though the loss of speed of the gravitational corpuscles was explicitly stressed by Fatio as a crucial element of his theory. Le Sage sent in a letter to Boscovich the beginning of Fatio's Latin poem (modeled on Lucretius) on the subject of his theory of gravitation, and told him that he wanted to publish it, but Boscovich did not agree, arguing that it would be too hard for most people to understand if it is published in Latin. Le Sage was worried about the possibility that people might think he had gotten the idea for the gravitation theory from Fatio, because he went to the trouble of making a "certificate", and having it signed by the mathematician Pfleiderer and the astronomer Mallet (two friends of Le Sage), stating that, except for a copy made by Abauzit in 1758, Le Sage saw no papers of Fatio before 1766, and in these papers there was nothing