Concerning Virgins is a series of letters; St. Ambrose wrote to his sister, Manellia, These, perhaps Ambrose's earliest writings, were written in 377 CE. Written in a rather light-handed non-technical style they appear as ethical guides to women who are contemplating entering nunneries. More importantly, they set the tone for Ambrose's later writing on ethics. Concerning Virgins was referred to by other patristic writers including St. Jerome, St Augustine and Cassian, and are now included in the extra-biblical cannon of the early church fathers.