From Dom Guéranger's The Liturgical Year.
Palestrina, the ancient Præneste, sends a representative to Mary’s court to-day, in the person of its valiant and gentle martyr, Agapitus. By his youth and his fidelity, he reminds us of that other gracious athlete, the acolyte Tarcisius, whose victory, gained on August 15, is eclipsed by the glory of Mary’s queenly triumph. During the persecution of Valerian, and just before the combats of Sixtus and Laurence, Tarcisius, carrying the body of our Lord, was met by some pagans, who tried to force him to show them what he had; but, pressing the heavenly treasure to his heart, he suffered himself to be crushed beneath their blows rather than 'deliver up to mad dogs the members of the Lord.’[4] Agapitus, at fifteen years of age, suffered cruel tortures under Aurelian. Though so young he may have seen the disgraceful end of Valerian; while the new edict, which enabled him to follow Tarcisius to Mary’s feet, had scarcely been promulgated throughout the empire, when Aurelian, in his turn, was cast down by Christ, from whom alone kings and emperors hold their crowns.
Prayer
Lætetur Ecclesia tua, Deus, beati Agapiti Martyris tui confisa suffragiis; atque ejus precibus gloriosis, et devota permaneat, et secura consistat. Per Dominum.
Let Thy Church rejoice, O God, relying on the intercession of blessed Agapitus, Thy martyr; and by his glorious prayers, may she remain devout, and be securely supported. Through, etc.