Pëtr Iakovlevich Chaadaev was a Russian thinker and writer. He was a member of the old nobility (his mother's father was the celebrated historian Mikhail Mikhailovich Shcherbatov [1733–1790]). He studied at Moscow University and participated in the great war of 1812 and in the subsequent campaign against Napoleon Bonaparte in Europe. In 1816–1817, while an officer in the Hussars, he met and became friends with Aleksandr Sergeevich Pushkin (1799–1837), who in his young years dedicated three letters in verse to Chaadaev. In 1821 Chaadaev resigned from military service, cutting short what had promised to be a brilliant career. From 1823 to 1826 he traveled in Europe (England, France, Italy, Switzerland, and Germany), where he became acquainted with Friedrich Wilhelm Joseph von Schelling and Hugues Félicité Robert de Lamennais, whose religious-philosophical ideas made a profound impression on him. At that...