Alexandre von HUMBOLDT (1769-1859). L.A.S., Berlin April 5, 1806, [to botanist André Thouin]; 2 1/2 pages in-4. Beautiful letter on botany. He sends Thouin, via M. de La Foret, the Emperor's minister plenipotentiary in Berlin, some seeds from the Jardin Royal des Plantes, in the hope that he will find some species he does not yet possess. He lists some of the 80 living species from the seeds he and Bonpland brought back: mimosa, ferns, Bonplandia, etc. "Several plants from Orenoque and Perou are already flowering"... Their friend Willdenow hopes "that the King will build large greenhouses this year. Indeed, our Garden is beginning to grow rich. Mr. Willdenow took charge of it with 1,200 species, and today we grow 6,800. But the plants are all very young"... He himself has not been able to work as much as he would have liked: "I feel very unhappy in a country where the ungrateful soil is barely covered with a few plants. I am burning with desire to be able to leave Europe again and bring you seeds from a part of Asia which has hardly been visited. I dare to flatter myself that my name is not entirely forgotten among you. My eyes are fixed daily on your shrine, as the Muslim turns every morning to Mecca"... He salutes Fourcroy, Vauquelin, Jussieu, Desfontaines, La Marck, Cuvier, Geoffroy, Duméril, Deleuze, Bonpland, Gay-Lussac...