Rousseau had the greatest difficulty in composing his works, being extremely defective in the gift of memory. He could never learn six verses by heart. In his _Confessions_ he says--"I studied and meditated in bed, forming sentences with inconceivable difficulty; then, when I thought I had got them into shape, I would rise to put them on paper. But lo! I often entirely forgot them during the process of dressing!" He would then walk abroad to refresh himself by the aspect of nature, and under its influence his most successful writings were composed. He was always leaving books which he carried about with him at the foot of trees, or by the margin of fountains. He sometimes wrote his books over from beginning to end, four or five times, before giving them to the press. Some of his sentences cost him four or five nights' study. He thought with difficulty, and wrote with still greater. It is astonishing that, with such a kind of intellect, he should have been able to do so much. The summer study of the famous Buffon, at Montbar, is still shown, just as he left it. It is a little room in a pavilion, reached by mounting a ladder, through a green door with two folds. The place looks simplicity itself. The apartment is vaulted like some old chapel, and the walls are painted green. The floor is paved with tiles. A writing-table of plain wood stands in the centre, and before it is an easy chair. That is all! The place was the summer study of Buffon. In winter, he had a warmer room within his house, where he wrote his _Natural History_. There, on his desk, his pen still lies, and by the side of it, on his easy chair, his red dressing-gown and cap of gray silk. On the wall near to where he sat, hangs an engraved portrait of Newton. There, and in his garden cabinet, he spent many years of his life, studying and writing books. He studied his work entitled _Epoques de la Nature_ for fifty years, and wrote it over _eighteen times_ before publishing it! What would our galloping authors say to that? Buffon used to work on pages of five distinct columns, like a ledger. In the first column he wrote out the first draught; in the second he corrected, added, pruned, and improved; thus proceeding until he had reached the fifth column, in which he finally wrote out the result of his labor. But this was not all. He would sometimes re-write a sentence twenty times, and was once fourteen hours in finding the proper word for the turning of a period! Buffon knew nearly all his works by heart. On the contrary, Cuvier never re-copied what he had once written. He composed with great rapidity, correctness, and precision. His mind was always in complete order, and his memory was exact and extensive.