Library Eusebius of Caesarea Life of Constantine
Book 4, Chapter 32: Of Constantine's Oration which he wrote to the Assembly of the Saints.
The emperor was in the habit of composing his orations in the Latin tongue, from which they were translated into Greek by interpreters appointed for this special service. One of the discourses thus translated I intend to annex, by way of specimen, to this present work, that one, I mean, which he inscribed To the assembly of the saints,
and dedicated to the Church of God, that no one may have ground for deeming my testimony on this head mere empty praise.
English translation by Ernest Cushing Richardson, in Nicene and Post-Nicene Fathers, Series II, Vol. I (eds. Philip Schaff and Henry Wace; Buffalo: Christian Literature Publishing Co., 1890). Public domain. Digital text via New Advent Church Fathers.