The Invention of Nature

When Humboldt was not writing, he was conducting experiments and comparing observations with those of other scientists. His correspondence was prodigious. He bombarded colleagues, friends and strangers with queries on topics as wide-ranging as the introduction of potatoes to Europe, detailed statistics on the slave trade or the latitude of the most northern village in Siberia. Humboldt corresponded with colleagues across Europe but also received letters from South America about the growing resentment against Spanish colonial rule. Jefferson dispatched reports about advances in transportation in the United States and added that Humboldt was regarded as one of the ‘great worthies of the world’ – and in return Humboldt sent Jefferson his latest publications. Joseph Banks, the president of the Royal Society in London, whom Humboldt had met in London two decades previously, remained another faithful correspondent. Humboldt sent him dried plant specimens from South America and his publications, while Banks used his own international network whenever Humboldt needed some information.

In Paris Humboldt rushed from one place to another. He lived, as a visiting German scientist remarked, in ‘three different houses’ – so that he could work and rest whenever and wherever he needed. One night he slept at the Paris Observatory, grabbing a few hours’ sleep between gazing at the stars and taking notes, while the next he stayed with his friend Joseph Louis Gay-Lussac at the École Polytechnique or with Bonpland.¹ In the mornings Humboldt made his rounds between 8 and 11 a.m., visiting young savants all over Paris. These were Humboldt’s so-called ‘garret-hours’, as one colleague teased, because these impoverished scientists usually lived in cheap attic rooms.

One such new friend was François Arago, a talented young mathematician and astronomer who worked at the observatory and the École Polytechnique. Like Humboldt, Arago had a taste for adventure. In 1806, at the age of twenty, self-taught Arago had been sent by the French government on a scientific mission to the Balearic Islands in the Mediterranean Sea, but had been arrested by the Spanish who had suspected him of espionage. For a year Arago had been incarcerated in Spain and Algiers but had finally escaped in summer 1809 – with his precious scientific notes hidden under his shirt. When Humboldt heard about Arago’s daring escape, he wrote to him immediately in order to arrange a meeting. Arago quickly became Humboldt’s closest friend – perhaps not coincidentally at the exact moment when Gay-Lussac married.

Arago and Humboldt saw each other almost every day. Working together and sharing results, they had heated discussions that sometimes ended in fights. Humboldt had a big heart, Arago said, but occasionally also a ‘malicious tongue’. Their friendship could be tempestuous. One of them would storm off ‘sulking like a child’, a colleague observed, but they never remained angry for long. Arago was one of the few people whom Humboldt trusted unconditionally – he could show him his fears and self-doubts. They were like ‘Siamese twins’, Humboldt later wrote, and their friendship was the ‘joy of my life’. They were so close that Wilhelm von Humboldt became concerned about their relationship. ‘You know his passion to be only with one person,’ Wilhelm told his wife Caroline, and now Alexander had Arago ‘from whom he did not want to be separated’.

This was not the only issue that Wilhelm had with his brother. He continued to disapprove of Alexander’s decision to stay in Paris, the heart of enemy territory. Wilhelm himself had returned to Berlin from Rome in early 1809 when he had been made Minister of Education. By then Alexander had moved to Paris but Wilhelm had been furious when he had seen that the family’s estate at Tegel had been plundered by French soldiers after the Battle of Jena and that his brother hadn’t even bothered packing up the house to protect its contents. ‘Alexander could have rescued everything,’ he complained to Caroline.

Wilhelm was upset with his brother. Unlike Alexander, Wilhelm was serving his country. First he had left his beloved Rome to overhaul the Prussian education system and establish Berlin’s first university, and then, in September 1810, Wilhelm had moved to Austria as the Prussian ambassador in Vienna. Wilhelm was fulfilling his patriotic duty. He was helping to draw Austria closer as an ally to Prussia and Russia to renew the fighting against France.