by St. Ambrose
From the days of the apostles there were some Christians who devoted themselves to God in a life of chastity, as the state of Virginity is even commended in holy Scripture by both our Lord and St. Paul. Later, it would become common for some to make a promise or vow in the presence of a bishop or member of the clergy as Ambrose’s sister, Marcellina, did. The terms, vow, taking the veil, and profession, were already in common use by St. Ambrose’s day. These virgins lived at home with their parents during times of persecution.
St. Ambrose would address the subject with his flock and, at the request of his sister Marcellina, recorded his teaching in the following three books. In the first book he treats of the dignity of Virginity, and states his reason for writing. In the second book, he gives examples and instances of the character and manner of life of virgins, such as Thecla, a disciple of St. Paul. In the third book he goes through a summary of the address given by Pope Liberius, when Marcellina received the veil before a large congregation. Some cautions are introduced by St. Ambrose against excessive austerity, and instead of some outward acts, prayer and the practice of interior virtues are recommended. He also broaches the subject of certain virgins who had committed suicide rather than lose their chastity.
Source Used: Nicene and Post-Nicene Fathers, Second Series, Vol. 10. Translated by H. de Romestin, E. de Romestin and H.T.F. Duckworth. Edited by Philip Schaff and Henry Wace. (Buffalo, NY: Christian Literature Publishing Co., 1896.)