The Prussian traveler and scientist Alexander von Humboldt (1769-1859) and the American Thomas Jefferson (1743-1826) were two among many intermediaries participating in the transfer of ideas, impressions, and knowledge between the Old and the New World. Because the two men held prominent positions in society, their respective ideas of Europe and America have had a particularly far-reaching historical effect.1 These two cosmopolitan thinkers demonstrated the importance of transatlantic communication in the open exchange of political as well as scientific ideas and information. As leading minds of the Enlightenment, they saw clearly the deficiencies of European society, and for them the United States served as a hopeful experiment for the application of their ideas to create a new form of society.2 In order to effect these social improvements and promote scientific progress, both Humboldt and Jefferson recognized the importance of an international network, whereby extensive correspondence could serve as a forum for discussion of respective works and the predominant questions of the time.
Who was this Prussian, and what circumstances led to his personal acquaintance with the third president of the United States? Alexander von Humboldt was born in Berlin in 1769 to an aristocratic family.3 He became famous for his scientific expedition through the Spanish colonies of South America from 1799 to 1804, undertaken in the company of his French colleague Aimé Goujand Bonpland and for which he had been given special permission by the Spanish king, Carlos IV.4 Humboldt received no financial support for this journey, paying all expenses himself, an important detail that must be recognized both for its uniqueness and as evidence that no European government with possible imperialistic interests stood behind his enterprise. Thus, Humboldt could pursue his own scientific objective to try to understand the nature of and, according to enlightened precepts, take measurements about every component of the New World, such as plants, animals, minerals, and climate. As a result, his contribution to science was not focused on one particular field but rather on the method he used to find the interconnections among the different branches of science.
After his expedition through Spanish America, Humboldt, accompanied by Bonpland, visited the United States from 20 May to 30 June 1804, where he met several times with President Jefferson and members of his cabinet.5 Even before their first personal encounter, Humboldt had introduced himself in a letter to Jefferson as an authority on the president's writings and had expressed admiration and respect for his enlightened intellect, his work, and his liberal ideas.6 Influenced by his identification with the ideals of the American independence movement, as well as the early goals of the French Revolution, Humboldt was impressed by the democratic form of American society, which he saw as a model for other parts of the Western Hemisphere as well as for European nations.
Jefferson, too, believed that Humboldt had something of particular interest to him. By the time the two men met in 1 804, Jefferson had reached the pinnacle of his career. As author of the Declaration of Independence, he stood out as one of the essential Founding Fathers. Then as wartime governor and emissary to France, he helped give concrete form to the ideals set forth in the Declaration. Now he served as third president of the new American nation. Throughout all the political tumult of the republic's early years, however, Jefferson had not abandoned his curiosity for the natural world. He therefore welcomed the Prussian visitor as a kindred spirit in the quest for discovery of new scientific knowledge. Moreover, Humboldt's travels and discoveries would prove useful to Jefferson as his nation expanded rapidly to the west. Humboldt's materials and maps from the Spanish colonial archives contained hitherto unknown data on …