Library Eusebius of Caesarea Life of Constantine
Book 3
Chapter 9: Of the Virtue and Age of the Two Hundred and Fifty Bishops
Of these ministers of God, some were distinguished by wisdom and eloquence, others by the gravity of their lives, and by patient fortitude of character, while others again united in themselves all these graces. There were among them men whose years demanded veneration: others were younger, and in the prime of mental vigor; and some had but recently entered on the course of their ministry. For the maintenance of all ample provision was daily furnished by the emperor's command.
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.