She was born in Rome and reared in the love of Christ. She secretly left her parents' house and traveled by ship to Alexandria, where she found lodging with four virtuous pagan maidens. By her example and counsel these four were in time led to abandon idolatry and embrace Domnica's faith. The five then sailed to Constantinople, where it is said that the Patriarch Nectarius (October 11) was notified of their coming by an angel and met them at the dock. The Patriarch baptized the four maidens himself, giving them the names Dorothea, Evanthia, Nonna and Timothea, then settled them and Domnica in a monastery.
Soon the fame of Domnica's pure life, wise teaching, and wondrous healings spread throughout the city, and even the Emperor Theodosius, with the Empress and his court, came to see her. Soon the crowds made it impossible for her and her sisters to live the heavenly life for which they had entered the monastery; so they relocated the monastery to a remote, demon-haunted location where