Quotations from Humboldt, "Personal Narrative" last modified:1/16/13

…we forgot that there might be dangers descending steep slopes covered with a smooth, slippery grass in the dark.

It was half past four in the afternoon when we finishe dour observations [measuring the altitude of the mountain La Silla in Venezuela]. Satisfied with the success of our journey we forgot that there might be dangers descending steep slopes covered with a smooth, slippery grass in the dark. We did not arrive at the valley bottom until ten at night. We were exhausted and thirsty after walking for fifteen hours, practically without stopping. The soles of our feet were cut and torn by the rough, rocky soil and the hard, dry grass stalks, for we had been forced to pull our boots off as the ground was too slippery. We spent the night at the foot of La Silla. Our friends at Caracas had been able to follow us on the summit with binoculars. They liked hearing our account of the expedition but were not happy with the result of our measurements, for La Silla was not as high as the highest mountains in the Pyrenees.

from Alexander von Humboldt, Jaguars & Electric Eels, translated by Jason Wilson.
London: Penguin Books, 1995. p. 17-18.

Humboldt's travel through the Americas began in 1799 and ended in 1804. The "Personal Narrative" comprises the final three volumes of his "Voyage aux régions équinoxiales du Nouveau Continent", which comprises thirty-five volumes, and was written betweeen 1805 and 1834. Thus Humboldt is recollecting events and emotions that span not only the years of his travel, but those well before it; and he wrote his narration after the travel (sometimes many years after its end). The title "Jaguars & Electric Eels" was supplied for this translation and edition, and is not by Humboldt.