Evagrius Ponticus was a Christian monk and theologian who lived in the 4th century. Born in what is now Turkey, he became a prominent figure in the early monastic movement. Evagrius is best known for his writings on spirituality and asceticism, which influenced later Christian thought. He emphasized the importance of inner contemplation and the struggle against sin, particularly through his concept of the "eight evil thoughts," which later evolved into the seven deadly sins. His works laid the groundwork for later monastic writers, including John Cassian and Benedict of Nursia.