Wulf details a perilous moment in the life of Alexander von Humboldt. On June 23, 1802, Humboldt and his three companions were navigating a treacherous ascent of Chimborazo, an inactive volcano in the Andes, then believed to be the world’s highest mountain. The narrative captures their dangerous climb at 17,000 feet above sea level, describing the physical challenges they endured: numbing cold, icy winds, and treacherous terrain that threatened their safety at every step. Their equipment was minimal, consisting of a barometer, thermometer, sextant, an artificial horizon, and a “cyanometer” to measure the blueness of the sky. Humboldt’s scientific zeal is highlighted as he continued to make observations and record data despite the extreme conditions.

This early adventure sets the stage for understanding Humboldt’s impact on natural science. His observations on this climb, particularly the distribution of plants and his realization of nature as a connected whole, foreshadowed his future theories. This experience on Chimborazo epitomizes Humboldt’s approach to science—immersing himself in harsh and challenging environments to observe and document the natural world firsthand.

Wulf uses this dramatic episode to underscore Humboldt’s innovative approach to natural science, which combined rigorous empirical data collection with a deep appreciation for the interconnectedness of nature.