CELESTIUS. - Leading figure of Pelagianism, he was probably a native of Italy. He practiced law in Rome, where around 405 he met Pelagius and accepted his doctrines. As an orator, skilled in every dialectical artifice, energetic, bold, and scheming, he delighted in emphasizing the provocative aspects of Pelagian doctrines, such as the denial of original sin (one might say that the "Celestian heresy," as contemporaries of St. Augustine refer to it, consisted precisely in this denial), the relative uselessness of Baptism, and the incompatibility of grace with human freedom. Anticipating the sack of Rome by the Visigoths, he went to Syracuse (409) and then to Carthage (410). Hoping to be ordained a priest there, he remained while Pelagius went on to Palestine. Soon his doctrines attracted the attention of the deacon Paulinus, formerly secretary to St. Ambrose, who denounced him to Aurelius, bishop of Carthage. The latter had him condemned by a council convened for this purpose in 411. C. appealed to Rome but instead went to Ephesus. Innocent I confirmed the condemnation (27 Jan. 417), though hinting at the possibility of pardon in case of repentance. Meanwhile, C. had managed to be ordained a priest in Ephesus; but soon, because of his propaganda, he was expelled from there as well, and shortly afterward from Constantinople. He then returned to Rome, where the new pope, Zosimus, seemed inclined to review the condemnation. Celestius’ improper and scheming conduct ruined everything. The emperor ordered his expulsion (30 Apr. 418), and Zosimus confirmed the condemnation (cf. the *Epistola Tractoria* of summer 418). The exile, protected by devoted friends, managed to evade arrest and even dared to reappear in Rome in 423 and in Constantinople in 429. From then on, all trace of him is lost. He probably died in 431.
Various writings are attributed to him: *Three Letters on the Monastic Life*; *The Book Against the Transmission of Original Sin*; *Definitions*, etc. Of all these works, only fragments remain, collected by J. Garnier in his edition of the works of Marius Mercator (Paris 1673), reprinted in PL 48, 497 ff.