It is a trite remark that diamonds can be polished only by diamond dust. Whatever the rude processes were to which the rude nature of the young Corsican was subjected, the result was remarkable. Latin he disliked, and treated with disdainful neglect. His particular aptitudes were for mathematics, for geography, and above all for history, in which he made fair progress. His knowledge of mathematics was never profound; in geography he displayed a remarkable and excellent memory; biography was the department of history which fascinated him. In all directions, however, he was quick in his perceptions; the rapid maturing of his mind by reading and reflection was evident to all his associates, hostile though they were. The most convincing evidence of the fact will be found in a letter written, probably in July, 1784, when he was fifteen years old, to an uncle,--possibly Fesch, more likely Paravicini,--concerning family matters.[4] His brother Joseph had gone to Autun to be educated for the Church, his sister (Maria-Anna) Elisa had been appointed on the royal foundation at Saint-Cyr, and Lucien was, if possible, to be placed like Napoleon at Brienne. The two younger children had already accompanied their father on his regular journey to Versailles, and Lucien was now installed either in the school itself or near by, to be in readiness for any vacancy. All was well with the rest, except that Joseph was uneasy, and wished to become an officer too. [Footnote 4: Du Casse, Supplément à la Correspondence de Napoléon Ier, Vol. X, p. 50. Masson, I, 79-84.]