2. De Virginibus. Three books concerning Virgins, addressed to his sister Marcellina in the year 377, probably, like most of the treatises of St. Ambrose, revised from addresses, the first of which was delivered on the festival of St. Agnes, January 21. This would seem to have been perhaps the very earliest of the writings of St. Ambrose, judging from the opening chapter. The treatise is referred to by St. Jerome, St. Augustine, Cassian, and others.