Following an invitation by Czar Nicholas I, Humboldt travels through the vast expanse of the Eurasian continent all the way to the Chinese border. At the end of the journey, he and his companions will have travelled more than 18000 kilometres. While Humboldt is studying nature – mountains and rocks, animal and plant life and especially the climate – he also makes his way through an empire in a phase of political repression. The great scientist was not immune to political constraints. The travel correspondence between Humboldt and the Russian finance minister, his letters to his brother Wilhelm and his friend François Arago as well as the report of his companion Gustav Rose make for a polyphonous account of the expedition, masterfully arranged by Oliver Lubrich. The collection of letters paints a lively picture of the man who was, even then, an internationally respected scholar, but also a compassionate brother and friend.