The historiosophical views of Pyotr Chaadaev (1794–1856) have been widely discussed and studied since the publication of the first Philosophical Letter to the Lady in the journal Telescope in the autumn of 1836. However, the range of the available works of Chaadaev was limited for a long time. Thus, Chaadaev’s five of the eight Philosophical Letters remained unknown until 1935, and the number of his letters that were studied was limited until the last few decades. The article aims to support the thesis of the fundamental consistency of the key provisions of Chaadaev in the last quarter of his life, from the completion of the Philosophical Letters series until his death. The author interprets the evolution of Chaadaev’s assessments of both “the future of Russia” and specific intellectual ideas of the Russian thought as a manifestation of his strong and constant principal position for the variations observed in the 1830s until the first half of 1850s which fit into the original conceptual scheme. Chaadaev’s assessments of the Slavophil intellectual movement within Russian thought and the Eastern Church (meaning only the Russian Orthodox Church) underwent the most significant changes. On the one hand, Chaadaev provided new estimates and returned to previous ones, which proves his saving of his original point of view. On the other hand, the changes in the assessment of Orthodoxy turn out to be a continuation and extension of the original approach to the interpretation of the place of Russia in world history.