49 For virginity is a difficult virtue; that one be able to embrace it there is needed not only a strong and declared determination of completely and perpetually abstaining from those legitimate pleasures derived from marriage; but also a constant vigilance and struggle to contain and dominate rebellious movements of body and soul, a flight from the importunings of this world, a struggle to conquer the wiles of Satan. How true is that saying of Chrysostom: "the root, and the flower, too, of virginity is a crucified life." For virginity, according to Ambrose, is as a sacrificial offering, and the virgin "an oblation of modesty, a victim of chastity." Indeed, St. Methodius, Bishop of Olympus, compares virgins to martyrs, and St. Gregory the Great teaches that perfect chastity substitutes for martyrdom: "Now, though the era of persecution is gone, yet our peace has its martyrdom, because though we bend not the neck to the sword, yet with a spiritual weapon we slay fleshly desires in our hearts." Hence a chastity dedicated to God demands strong and noble souls, souls ready to do battle and conquer "for the sake of the kingdom of heaven."
Source: Sacra Virginitas (Vatican.va)