589–816

The Filioque in the West: Toledo (589), Friuli (796), Aachen (809) and Pope Leo III

The Niceno-Constantinopolitan Creed says that the Spirit "proceeds from the Father"; according to González, this does not deny procession from the Son as well, but in the West people more often said "from the Father and the Son," and in the East "from the Father through the Son." At the Synod of Toledo in 589 the word "filioque" ("and from the Son") was added to the creed; the interpolation spread from Spain to Gaul and the rest of the West. Under Charlemagne the Filioque became an important doctrinal issue: against adoptionism, Paulinus of Aquileia argued that the consubstantiality of the Father and the Son requires teaching that the Spirit proceeds from both, and the council of Friuli (796) produced the earliest document of the Western version of the creed with the Filioque. The Synod of Aachen (809) declared the Greek formula heretical, but Pope Leo III, while accepting the teaching itself, refused to insert the interpolation into the creed.