P. I︠A︡ Chaadaev

7 June 1794 – 26 April 1856

Pyotr or Petr Yakovlevich Chaadayev (Russian: Пётр Я́ковлевич Чаада́ев; also spelled Chaadaev, or Čaadajev) was a Russian philosopher. He was one of the Russian Schellingians.