95% sureThese words were traced back to where they first appeared. That source is listed below.
What turned up
Letters of Alexander von Humboldt to Varnhagen von Ense, trans. Friedrich Kapp (Rudd & Carleton, 1860; Gutenberg #67420). Letter 16, Humboldt to Varnhagen, Oct. 24, 1834, signed A. V. Humboldt.
Work
Letters to Varnhagen von Ense
Occasion
1834 · explaining his plan for writing Kosmos, the book describing the whole of nature
Sources checked
gutenberg.orgChecked using claude-sonnet-5, 21 August 2026Kapp translation, Letters of Alexander von Humboldt to Varnhagen von Ense; letter of Oct. 24, 1834 describing the plan for Kosmos
Nothing made from these words yet — Storyfaire is where they get made.