 Eriugena first came to historical notice when he was commissioned by two French bishops—Archbishop Hincmar of Rheims and Bishop Pardulus of Laon—to refute a treatise by a Saxon monk, Gottschalk (806–68), a priest of Orbais in the diocese of Soissons, who interpreted St. Augustine as teaching a “twofold” or “twin predestination” (gemina praedestinatio) of the elect to heaven and of the damned to hell, based on the opinion of St. Isidore, Sententiae II, 6, I (PL 83: 606a). Gottschalk had already been condemned by a synod at Mainz in 848 and another at Quierzy in 849 and had been imprisoned in the abbey of Hautvillers (where he remained until his death in 868), but Prudentius, the bishop of Troyes, appeared to side with him. Hincmar was worried that Gottschalk’s side was attracting powerful supporters and he engaged Eriugena to write a strong rebuttal. Eriugena’s response, De divina praedestinatione (On Divine Predestination, c. 851, see Madec edition, 1978), a treatise of nineteen chapters, which survives in a single manuscript, is a robust rebuttal of Gottschalk. Eriugena rejects any divine predestination to evil by an appeal to God’s unity, transcendence, and goodness. While purporting merely to interpret Augustinian texts, this early theological treatise is philosophically significant for its rationalistic, dialectical analysis of key theological concepts and its reliance on argument rather than scriptural citation. In this treatise, Eriugena, citing Augustine’s De uera religione 5.8, PL 34: 126, claims “that true philosophy is true religion and conversely that true religion is true philosophy”. As one gloss in the Annotationes in Marcianum attests: “no one enters heaven except through philosophy” (nemo intrat in celum nisi per philosophiam, Annotationes 57.15, AM: 64). Eriugena then argues that philosophy has four principal parts—division, definition, demonstration, and resolution—and the pursuit of this fourfold method of reasoning will lead to truth. This focus on dialectic as the path to truth is a constant theme of Eriugena’s philosophy, one recognized by his contemporaries.