[1] Four letters written by him on that occasion, all dated 15 March 431, together with a few others, to the African bishops, to those of Illyria, of Thessalonica, and of Narbonne, are extant in re-translations from the Greek; the Latin originals having been lost.
Celestine strongly opposed the Novatians in Rome; as Socrates Scholasticus writes, "this Celestinus took away the churches from the Novatians at Rome also, and obliged Rusticulus their bishop to hold his meetings secretly in private houses.
As St. Vincent of Lerins reported in 434: In a letter to certain bishops of Gaul, dated 428, Celestine rebukes the adoption of special clerical garb by the clergy.
He wrote: "We [the bishops and clergy] should be distinguished from the common people [plebe] by our learning, not by our clothes; by our conduct, not by our dress; by cleanness of mind, not by the care we spend upon our person".
He was buried in the cemetery of St. Priscilla in the Via Salaria, but his body, subsequently moved, now lies in the Basilica di Santa Prassede.