ALEXANDER VON HUMBOLDT (1769-1859) HANDWRITTEN AND SIGNED ENVELOPE COVER, “A. V. Humboldt”, 5.25 X 4.5, postmarked 21 JUL 1834, Munich, by the German polymath, geographer, naturalist, explorer, and the first person to describe the phenomenon and cause of human-induced climate change (1800 & again in 1831). His 1799, 6,000 mile expedition through Central and South America doing quantitative work on botanical geography laid the foundation for the field of biogeography. He spent over 20 years publishing his findings. Later in life he worked on his multi-volume treatise, Kosmos, in which he sought to unify diverse branches of scientific knowledge and culture. This envelope, which is written in German, is being used much like a note that is directing the recipient to pass the contents along to another identified person. It is in fine condition with his large red seal still intact.