German naturalist and explorer (1769–1859) who wrote Kosmos, a massive five-volume study which attempted to unify the various branches of Man’s knowledge. ANS on an off-white 4 x 2.5 clipped slip affixed to a slightly larger sheet. Humboldt pens a brief, untranslated note in German in his graceful hand, signed in ink, “A. V. Humboldt,” adding the date, “June 1855.” Uniform toning, some trivial foxing, and light rippling from the adhesive, otherwise fine condition. Sold together with a vintage portrait engraving. RRAuction COA.