Service as a Deaconess
Theosebia held the office of deaconess in the church at Nyssa, where her brother Gregory served as bishop. According to the tradition recorded of her, her duties included caring for the sick, distributing food to the poor and to wanderers, raising orphans, and preparing women for baptism.
She is remembered as having maintained her virginity throughout her life. Tradition also relates that she shared in the hardships of her family, accompanying her brother Gregory of Nyssa during the three years of his exile.
Praise by Saint Gregory the Theologian
After Theosebia's death, Saint Gregory the Theologian (Gregory of Nazianzus) wrote a letter of condolence to Gregory of Nyssa in which he eulogized her. In this letter, preserved as his Epistle 197, he addressed her as a true yoke-fellow of a priest and praised her in lofty terms as an ornament of the Church.
The wording of Gregory's letter has been the subject of scholarly discussion, and some modern scholars have read his praise as evidence of an unusually prominent ecclesiastical standing. The Orthodox tradition venerates her as a deaconess.
Question of Her Relationship to Gregory of Nyssa
The precise nature of Theosebia's relationship to Gregory of Nyssa is debated among historians. Gregory of Nazianzus's condolence letter refers to her as a sister, and Orthodox tradition holds her to be the sister of Basil the Great, Gregory of Nyssa, and Peter of Sebaste.
Some scholars have proposed instead that she may have been the wife of Gregory of Nyssa, noting that his own writings indicate he was married. The sources do not resolve the question with certainty, and the family identification as a sister is the one carried by the Orthodox commemoration.
