Methodius: The Banquet of the Ten Virgins; Or, Concerning Chastity
While I don't necessarily agree with all the conclusions of this dialogue, it can hardly be denied that it is truly an excellent work. It is especially useful to compare it to some of the extremes the Western church later fell into as regards marriage vs. chastity. This dialogue is even more useful for us as Protestants who are perhaps not used to thinking of the role of virginity in salvation:
Wherefore God, pitying us who were in such a condition, and were able neither to stand nor to rise, sent down from heaven the best and most glorious help, virginity, that by it we might tie our bodies fast, like ships, and have a calm, coming to an anchorage without damage, as also the Holy Spirit witnesses. (IV.II)Our salvation comes miraculously through the virgin birth. And while we are not saved by Mary's virginity or any nonsense like that, virginity was nevertheless a key part of the work of our Savior. There's a work to be done (but not by me) comparing this work on virginity with the excellent work by Thomas Shepard's Parable of the Ten Virgins.