Part 1. Departure: Emerging Ideas
Wulf describes Humboldt's childhood with his emotionally distant mother. As a child his interests in nature and travel were not taken seriously. His mother, on whom he was financially dependent, insisted he become a civil servant. As a young man, Humboldt became friends with Goethe and other German intellectuals. His mother's death allowed him the freedom and financial independence needed to journey to the New World.
Part 2 Arrival: Collecting Ideas
Humboldt arrives in Venezuela with his companion Bonpland and begins his journey through Central and South America. He brought with him a plethora of scientific instruments. He chronicles his travels and the measurements he obtained using scientific instruments in his journals. Humboldt climbs Chimborazo, a volcano in the Andes, which was then believed to be highest mountain in the world. The trip concludes with his visit to the United States where he visited the White House to discuss science and politics with Thomas Jefferson before returning to Europe.
Part 3 Return: Sorting Ideas
Humboldt returns to Europe where he is greeted as a celebrity. He lives as an expat in Paris for seven months as he finds the city and its scientific culture more stimulating than that of Berlin. While in France, he meets a young Simon Bolivar, who is impressed with Humboldt's knowledge and passion for his home country of Venezuela, and they discuss South American politics. Humboldt returns to Prussia, to earn a salary in the King's court before returning to Paris. At this point he begins to work on several manuscripts based on his travels. The books are widely read. As Bolivar begins to plan and execute revolutions in South America, Humboldt publishes a series of books on the politics of Latin America that criticize colonialism.
Part 4 New Worlds: Spreading Ideas
Wulf discusses Humboldt's personal correspondence and influence on a young Charles Darwin, who attributed to Humboldt the inspiration for an interest in natural science leading to his voyage on the Beagle. Humboldt's influence on the American poet and philosopher Henry David Thoreau is explored. Humboldt's magnum opus Cosmos, where he talks of the interconnections of the natural world, is discussed.