In 1829, at the invitation of Emperor Nicholas I, the famous German naturalist Alexander von Humboldt organized an expedition across the European part of Russia, as well as across Siberia up to the border with China. Traveling throughout the empire, Humboldt, despite constant surveillance and the ban on speaking on public issues, sought to record Russian political reality. In his works, criticism of the repressive institutions of the empire is contained in the form of encrypted hints, but in correspondence the scientist shares his impressions much more openly. Oliver Luebrich's book is compiled from Humboldt's travel letters to the Minister of Finance Kankrin, his brother Wilhelm and his mathematician friend Arago, and also includes notes from Gustav Rose, Humboldt's companion. The letters provide a vivid insight into the dramatic circumstances of the expedition and the difficult situation of Humboldt himself, forced to engage in science under conditions of political censorship and choose between risky freethinking and compromising silence.