The Invention of Nature

Humboldt’s detailed analysis came to the surprising conclusion that temperatures were not the same along the same latitude as had been previously assumed. Altitude, landmass, proximity to oceans and winds also influenced heat distribution. Temperatures were higher on land than on sea, but also lower at higher elevations. This meant, Lyell concluded, that where geological forces had elevated the land, temperatures dropped accordingly. In the long term, he argued, this upward drift brought a cooling effect to the world climate – as the earth changed geologically, so did the climate. Years later, when pressed by a reviewer of Principles of Geology to define the moment of ‘a beginning’ of his theories, Lyell said it had been the reading of Humboldt’s essay on isotherms – ‘give Humboldt due credit for his beautiful essay’. In his own work, Lyell said, he had only given Humboldt’s climate theories a ‘geological application’.

Humboldt helped young scientists whenever he could, intellectually but also financially, no matter how difficult his own situation. So much so that his sister-in-law, Caroline, worried that his so-called friends exploited his kindness – ‘he eats dry bread, so that they can eat meat.’ But Humboldt didn’t seem to care. He was the hub of a spinning wheel, forever moving and connecting.

He wrote to Simón Bolívar to recommend a young French scientist who planned to travel through South America, as well as equipping the scientist with his own instruments. Similarly, Humboldt introduced a Portuguese botanist who intended to emigrate to the United States to Thomas Jefferson. The German chemist Justus von Liebig, who would later become famous for his discovery of the importance of nitrogen as a plant nutrient, recounted how meeting Humboldt in Paris had ‘laid the foundation of my future career’. Even Albert Gallatin, the former US Secretary of the Treasury, who had first met Humboldt in Washington and then again in London and Paris, found himself so inspired by Humboldt’s enthusiasm for indigenous people that he threw himself into studies of Native Americans in the United States. Today Gallatin is regarded as the founder of American ethnology; the reason for his interest, Gallatin wrote, was ‘the request of a distinguished friend, Baron Alexander von Humboldt’.

As Humboldt helped friends and fellow scientists to advance their careers and travels, his own chances of being allowed to enter India had dwindled to nothing. He fed his wanderlust with trips through Europe – Switzerland, France, Italy and Austria – but it wasn’t the same. He was unhappy. It was also becoming increasingly difficult to justify his decision to live in Paris to the Prussian king. Since Humboldt’s return from Latin America two decades earlier, Friedrich Wilhelm III had repeatedly pressed him to return to Berlin. For twenty years the king had paid him an annual stipend with no strings attached. Humboldt had always argued that he needed Paris’s scientific environment to write his books but the climate in the city and France had changed.

After Napoleon’s removal and imprisonment on the remote island of St Helena in 1815, the Bourbon monarchy had been reinstated with the crowning of Louis XVIII² – the brother of Louis XVI who had been guillotined during the French Revolution. Though absolutism had not returned to France, the country that had held the torch of liberty and equality had become a constitutional monarchy. Only one per cent of the French population was eligible to elect the lower house of parliament. Though Louis XVIII respected some liberal views, he had arrived in France from exile with a train of ultra-royalist émigrés who wanted to return to the old ways of the pre-revolutionary Ancien Régime. Humboldt had watched them coming back and had seen how they burned with hate and a desire for revenge. ‘Their tendency to absolute monarchy is irresistible,’ Charles Lyell had written to his father from Paris.

Then in 1820 the king’s nephew, the Duc de Berry – third in line to the throne – was murdered by a Bonapartist. After that there was no holding back the royalist tide any more. Censorship became harsher, people could be held without trial and the wealthiest people received a double vote. In 1823 the ultra-royalists gained the majority in the lower house of parliament. Humboldt was deeply upset, telling one American visitor that all it took was one look at the Journal des Débâts – a newspaper founded in 1789, during the French Revolution – to see how the freedom of the press had become curtailed. Humboldt was also beginning to feel uncomfortable at the way that religion, with all its constraints on scientific thinking, was reasserting its grip on French society. With the return of the ultra-royalists, the power of the Catholic Church rose. By the mid-1820s new church spires were rising across the Paris skyscape.