The Nativity of the Theotokos is observed in Eastern Christianity worldwide every September 21. This feast celebrates the birth of Mary, who was born to elderly parents, Joachim and Anna, after a long period of childlessness. According to Orthodox tradition, an angel announced to them that God had heard their prayers and they would have a child. The feast does not accept the doctrine of the immaculate conception of Mary, but it holds that she was kept free from actual sin by God's grace. The celebration, which dates back to the Byzantine Empire in the late 6th or early 7th century, begins with a mass and includes special prayers. Additionally, Eastern Christians typically complete their harvest by this date to give thanks for their well-being.