Today marks the 240th birthday of Alexander von Humboldt, an explorer, scientist, writer, and humanist who was the most famous intellectual of the age that began with Napoleon and ended with Darwin. The University of Chicago Press is publishing two books this fall that celebrate this seminal thinker. Laura Dassow Walls’s The Passage to Cosmos: Alexander von Humboldt and the Shaping of America traces Humboldt’s ideas from Cosmos—the book that crowned his career—to his 1799 journey to the Americas, where he first experienced the diversity of nature and of the world’s peoples—and envisioned a new cosmopolitanism that would link ideas, disciplines, and nations into a global web of knowledge and cultures. That voyage is also at the center of Stephen T. Jackson’s edition of Humboldt’s Essay on the Geography of Plants.
Walls and Jackson recently collaborated on this appreciation of Humboldt on his 240th anniversary. That Walls is an English professor and Jackson an ecologist would undoubtedly please Humboldt very much; he argued for interdisciplinarity across the humanities and sciences, and this essay is emblematic of that fertile exchange.

Mention “Darwin” to any literate audience in America and eyes will light up with recognition; mention “Humboldt,” and most faces will remain blank. Some might recall a Saul Bellow novel, a disappearing river in Nevada, an ocean current off Peru, a college town in California. But 150 years ago, it was Alexander von Humboldt’s name that would have lit up the room. A physician in Charleston, a lawyer in Peoria, a poet in Concord, or an army captain in San Francisco—all could have pulled some Humboldt volumes off the shelf and led a lively conversation about the famous German scientist. For in 1859, Humboldt’s, not Darwin’s, was the name that stamped the century. As Emerson said, “It is the age of Humboldt.”

2009, the “Year of Darwin,” marks the bicentennial of Darwin’s birth and the sesquicentennial of Origin of Species. But it also marks the sesquicentennial of Humboldt’s death, and September 14th is his 240th birthday. Sadly, only a few of us will pause to honor him, for in the United States his name has been largely forgotten. Yet he was one of the founders of our intellectual world. “We are all his family,” said his scientific colleagues; it was Humboldt’s writings that inspired Charles Darwin to embark for South America on the H.M.S. Beagle, and Humboldt who gave Darwin the intellectual tools he needed to craft his grand theory of evolution.
Humboldt’s influence reaches far beyond Darwin, spanning the natural and social sciences as well as the humanities. His fame was launched at the turn of the nineteenth century during a five-year voyage to the Americas: from 1799 to 1804 he explored the Orinoco and upper Amazon Rivers, trekked the Andean highlands, climbed Chimborazo to the highest elevation ever reached, interviewed the descendants of the Inca, toured the mines and ruins of central Mexico, studied the plantation economy of Cuba. He and his companion, the French botanist Aimé Bonpland, collected thousands of botanical, zoological, and geological specimens and made tens of thousands of measurements of temperature, humidity, and air pressure. On their way home to Europe, Humboldt stopped in Philadelphia, where he was feted by Charles Willson Peale, Caspar Wistar, and Benjamin Rush, who elected him an honorary member of the American Philosophical Society—Peale’s portrait of Humboldt still hangs in the Philadelphia College of Physicians. Humboldt traveled to Washington to meet Thomas Jefferson in the White House, where they spent days discussing politics, exploration, and natural history.
Back in Paris, then the scientific capital of the world, Humboldt exhausted his family fortune publishing the results of his expedition: essays, astronomical tables, botanical and zoological monographs, atlases, economic analyses, and the Personal Narrative of his travels—the set that accompanied Darwin on the Beagle. His Essay on the Geography of Plants laid the foundations for ecology and biogeography, his Political Essay on the Kingdom of New Spain (and a similar volume on Cuba) created the field of economic geography, and his ethnographies and drawings brought Native American languages, cultures, and monuments to the attention of the world. Humboldt invented graphical devices to display data and concepts that remain in use today, including the lines of equal temperature—isotherms—on the weather map you may have consulted this morning.
Above all, Humboldt invented a way of seeing that embraced all of physical nature, organic life, and human culture and history. He wove the sciences and the humanities together, recognizing the reciprocal influences among vegetation, landforms, water and atmosphere; among agriculture, industry, commerce and scientific inventions; among languages, the migrations of peoples, and the unique sense of place that stamps the poetry and art of every region. His “general physics of the earth” showed how spatial and temporal variation in climate controlled the structure of vegetation, the distribution of plant and animal species, and the features of human cultures across the globe. He believed that both science and the arts were crucial for human development, and during a time of international tension and conflict he hammered together the first international cooperative networks for scientific research. The environmental sciences—ecology, climatology, oceanography, geology, human geography, resource economics—are rooted in Humboldt’s work, which has been reborn in the last two decades as earth system science, which strives to integrate the processes governing the dynamics of the earth’s landforms, oceans, atmosphere, and ecosystems. This Humboldtian science underpins efforts to understand and mitigate the threat of global climate change.
America may have forgotten Humboldt today, but our republic held a special place in his heart. He proudly called himself “half an American,” and until the end of his life he corresponded with Jefferson, Madison, and dozens of other American scientists, scholars, and artists. Only weeks before his death, he celebrated George Washington’s birthday with American students in Berlin, who garlanded his head with the American flag. To him, the United States represented the best realization on earth of the principles of liberty and equality advanced by the Enlightenment, and Humboldt strove all his life to sell the American ideal to a skeptical Europe. When Americans refused to end slavery, Humboldt lent his name and his eloquence to American abolitionism. In turn, Americans peppered his name on their maps, giving it to towns and geographical features from coast to coast. In 1869, the centennial of his birth was celebrated as a national holiday. No library was complete without his Cosmos, Views of Nature, and Personal Narrative, writings that inspired not only countless naturalists but also poets, novelists, essayists, and artists. Poe and Whitman, Thoreau and Emerson, Catlin and Church, Olmsted and Muir all drew inspiration and ideas from Humboldt’s writings, ultimately launching the American environmental movement.
Humboldt’s gifts endure even if his name does not. His cosmopolitan vision, and his advocacy of political rights and freedoms—he was outspoken in defending the rights of Prussian Jews and other minorities to practice religion and hold public office—persists in the international human rights movement. He resurrected the word “Cosmos” from antiquity to name the overarching unity of human knowledge and natural beauty. While the unity of the sciences has fragmented into countless specialties, his vision survives in the conviction that underneath them all nature forms an interconnected whole. Today we need his vision more than ever, as we confront the challenges of fragmenting knowledge and the loss of political freedoms in a world of diminishing resources and rapid environmental change.