In California, a county, a bay, a university, and a state park all bear the name of Alexander von Humboldt, the Prussian naturalist whose fame was once regarded as second only to Napoleon.

“Yet Humboldt,” writes Andrea Wulf, a Humboldt biographer, “is almost forgotten in the English-speaking world.”

Born to wealth in 1769, Humboldt walked away from his aristocratic life in Berlin to embark on a five-year exploration of Latin America. His goal, he wrote, was to discover “the unity of nature.” He navigated the Orinoco River and walked thousands of miles through the Andes, climbing Chimborazo along the way — regarded incorrectly at the time as the world’s tallest peak.

Everywhere Humboldt went, he took measurements. He sketched hieroglyphs, transcribed indigenous vocabularies, gauged the blueness of the sky, and collected 60,000 botanical specimens.

Upon his return, he settled in Paris and published international best-sellers advancing the theory that all organisms were woven together in a “net-like intricate fabric.” He argued that the “insatiable avarice” of Spanish colonialists had caused incalculable harm to native cultures and stately forests.

His admirers included figures as diverse as Thomas Jefferson, Simón Bolívar, and Charles Darwin, who said that Humboldt’s writings inspired him to board the Beagle.

Over time, Humboldt’s namesakes became legion. Among them was a squid, a penguin, a glacier, an ocean current, and a lily. He never visited California. Even so, a pair of mariners exploring the north coast in 1850 named a bay after him. Humboldt County and Humboldt State Normal College, later renamed Humboldt State University, followed.

It was on this week in 1859, that Humboldt died at the age of 89. Yet even as American newspapers eulogized him as the “most remarkable man ever born,” he soon faded in the popular imagination.

About nine years after Humboldt’s death, the Scottish-American wanderer John Muir arrived in California, his head filled with the ideas of the great Prussian polymath. “How intensely I desire to be a Humboldt!” Muir wrote to a friend. Muir’s writings about the sanctity of the natural world later made him a giant of the environmental movement.

According to Wulf, many of Muir’s more famous lines — along with those of Henry David Thoreau and George Perkins Marsh — were derived from their reading of Alexander von Humboldt.