Nicene and Post-Nicene Fathers, Ser. II, Vol. VI: The Letters of St. Jerome.: Letter XCIV
Letter XCIV. From Dionysius to Theophilus.
In this letter (translated into Latin by Jerome) Dionysius, bishop of Lydda, praises Theophilus for his signal victories over Origenism and urges him to continue his efforts against that heresy. Written in 400 a.d.