Hincmar of Reims: De Una et Non Trina Deitate

This treatise by Hincmar, archbishop of Reims (c. 806–882), opposes the expression ‘trina deitas’ (‘threefold deity’). In the prologue he explains that some, taking occasion from the closing words of a hymn of unknown authorship, ‘Te trina Deitas unaque poscimus’, had begun to argue that just as God is three and one, so the deity may be called threefold and one. He names Ratramnus, monk of Corbie, who compiled a sizeable volume for Bishop Hildegar of Meaux by truncating and twisting passages of Hilary and Augustine. The work includes and refutes a schedule of Gottschalk on the same question, and an excerpt of Gottschalk’s letter to Ratramnus.

Hincmar’s concern was that speaking of a threefold deity implied three divinities, and he insisted that there is one deity in three persons; the sample quotes Ambrose on the unity of power in the Trinity. The dispute was an offshoot of his long conflict with Gottschalk of Orbais, and Hincmar ordered the phrase to be changed in the hymn in his diocese. The treatise is an important source for Carolingian Trinitarian debate and for the methods of patristic citation used by both sides.