1824-1871 1853-1900 1871-1944 19thcentury 20thcentury approximately1314-1391or1392 biography bulgakov churchhistory doctrines doctrinesorthodoxeasternchurch feodor history historyrusskai͡apravoslavnai͡at͡serkovʹ historytroit︠s︡e-sergievalavra orthodoxeasternmonasteries russia russia(federation) russkai︠a︡pravoslavnai︠a︡t︠s︡erkovʹ sergievposad sergiĭ solovyov sovietunion theologians theology vladimirsergeyevich