St. Sylvester, whom God appointed to govern his holy church in the first years of her temporal prosperity and triumph over her persecuting enemies, was a native of Rome, and son to Rufinus and Justa. According to the general rule with those who are saints from their cradle, he received early and in his infancy the strongest sentiments of Christian piety from the example, instructions, and care of a virtuous mother, who for his education in the sound maxims and practice of religion, and in sacred literature, put him young into the hands of Charitius or Carinus, a priest of an unexceptionable character and great abilities.
Being formed under an excellent master, he entered among the clergy of Rome, and was ordained priest by pope Marcellinus, before the peace of the church was disturbed by Dioclesian, and his associate in the empire. His behavior in those turbulent and dangerous times recommended him to the public esteem, and he saw the triumph of the cross by the victory which Constantine gained over Maxentius within sight of the city of Rome on the 28th of October, 312.
Pope Melchiades dying in January, 314, St. Sylvester was exalted to the pontificate, and the same year commissioned four legates, two priests, and two deacons, to represent him at the great council of the Western church, held at Arles in August, in which the schism of the Donatists, which had then subsisted seven years, and the heresy of the Quartodecimans were condemned, and many important points of discipline regulated in twenty-two canons. These decisions were sent by the council before it broke up with an honorable letter to pope Sylvester, and were confirmed by him and published to the whole church.
The general council of Nice was assembled against Arianism in 325. Socrates, Zozomen, and Theodoret, say that pope Sylvester was not able to come to it in person on account of his great age, but that he sent his legates. Gelasius of Cyzicus mentions, that in it Osius held the place of the bishop of Rome