9th–11th centuries

The Filioque in the East: Photius, On the Mystagogy of the Holy Spirit, and the Break of 1054

Photius called the Latins' teaching on the Spirit not the least of their blasphemies, deserving a thousand anathemas, and in his treatise On the Mystagogy of the Holy Spirit he asked: "Which of our fathers said that the Spirit proceeds from the Son?" He regarded the Lord's words about procession from the Father and the ecumenical councils as the highest authority, and proposed that Ambrose and Augustine be acknowledged as fathers, but as inferior to the "fathers of the fathers." The Greeks also raised a procedural objection: a creed formulated by a council could be expanded only by a general council of East and West. They saw the cause of the Filioque in confusing the Spirit's "sending" in the world (economy) with his eternal "procession" (theology). According to Lane, in the 11th century Rome too added the filioque, which hastened the break between Rome and Constantinople in 1054.