DOI : 10.1484/J.RHE.5.114483 THE QUESTION OF THE IMPACT OF DIVINE GRACE IN THE PELAGIAN CONTROVERSY HUMAN POSSE, UELLE ET ESSE ACCORDING TO PELAGIUS, JEROME, AND AUGUSTINE Pelagius’ first written reaction to Jerome’s polemical campaign against Pelagius in Palestine needs to be dated after the synod of Diospolis, held in December 415, convened to evaluate Pelagius’ orthodoxy. It seems that before Diospolis, Pelagius’ polemics re- mained at the level of oral charges, as reported by Jerome. 1 The acquittal of Pelagius at Diospolis may have emboldened him to confront Jerome directly by publishing a treatise of four books entitled Pro libero arbitrio, 2 which counters Jerome’s anti-Pela- gian writings. Unfortunately, Pelagius’ treatise has not been pre- served, apart from the passages quoted by Augustine in his De gratia Christi et de peccato originali, 3 and three further fragments edited by Souter more than a century ago. 4 As indicated by the title of the treatise, one of the main is- sues considered by Pelagius is human free will and its relation to 1 See, for example, Jerome, Epist. 133, 11. 2 For Pelagius’ publication of Pro libero arbitrio after the synod of Dio- spolis, see A u g u s t i n e, De gratia Christi et de peccato originali II, 14, 15, and II, 16, 17. 3 We lack a modern edition of these fragments, which has been an- nounced by W. Lીhr, Pélage et le pélagianisme (Les conférences de l’École pratique des hautes études, 8), Paris, Cerf, 2015, p. 72, n. 42. Another frag- ment is quoted in Augustine’s letter 186 and sermon 156, see J. Lીssl, Dating Augustine’s Sermons 151-156: Internal Evidence, in G. Partoens (ed.), Sancti Aurelii Augustini Sermones CLI-CLVI, CCSL 51/B, Turnhout, Brepols 2007, p. xxiii–lv (xlix–lv). 4 A. Souter, The Commentary of Pelagius on the Epistles of Paul: The Problem of its Restoration, in Proceedings of the British Academy, 2 (1905- 1906), p. 409-439; A. Souter, Another New Fragment of Pelagius, in Journal of Theological Studies, 12 (1910-1911), p. 32-35. These fragments are now published in PLS 1, 1539-1543. See also G. Mercati, Some New Fragments of Pelagius. I. Two New Fragments of Pelagius, in The Journal of Theological Studies, 8 (1907), p. 526-529.