Nil Sorsky (Russian: Нил Сорский, also Nilus of Sora and Nil Sorski) (c. 1433–1508) was a leader of the Russian medieval movement opposing ecclesiastic landownership (known as the "Non-possessors"). Nil Sorsky is venerated as a saint in the Russian Orthodox Church. His feast day is on the anniversary of his repose on May 7. In his teachings, he developed mystical and ascetical ideas along the lines of Gregory Sinaite's hesychasm, asking the believers to concentrate on their inner world and personal emotional experiences of faith as means for achieving unity with God.