The filioque clause refers to the words “and the Son” added to the third article of Latin text of the Niceno-Constantinopolitan Creed: “We believe … in the Holy Spirit, the holy, the lordly and life-giving one, proceeding forth from the Father and the Son [not found in its Greek version], co-worshipped and co-glorified with Father and Son.” The clause, presumably previously found in The Athanasian Creed, was added into the Creed by the anti-Arian Council of Toledo (589) under the leadership of Visigothic Spanish King Reccared. The usage of the interpolated Creed spread throughout the West, although not in Rome until 1014 when Pope Benedict VIII (1012-1024) ratified the interpolated Creed and made the filioque part of Roman liturgy for Sundays and feasts. Meanwhile, in the East, the Greeks understood that the Spirit proceeds from the Father “alone”– although they never added the word to the Creed. During the centuries, only slowly did the Latins and the Greeks increasingly recognize the significance of their differences and the ensuing Filioque Controversy was calamitous to the unity between the Eastern and Western churches. The centuries-old tension eventually broke the Eastern and Western communion. After a failed dialogue, on 16 July 1054, Cardinal Humbert went into Hagia Sophia and placed on its altar a bull of excommunication against Patriarch Michael Cerularius whom in turn pronounced anathema on the authors of the bull. The Great Schism, sometimes considered to be personal between Humbert and Cerularius, was devastating to the already fragile relationship between the Eastern and Western churches. Efforts to heal the communion were made. The Council of Lyon (1274) followed by the Council of Ferrara-Florence (1438-1445) finally paid off with the promulgation of a decree of union, the Laetentur Caeli, on 6 July 1439. However, the decree of union was rejected by many, especially in the East. Some accused the Latins of taking advantage of the political and military declination of Byzantium and forcing the Greeks to sign the decree. Although the Latins continue to acknowledge the ecumenicity of the two councils, they were denied by the Greeks who abandoned the short-lived union shortly after the fall of Constantinople. Thus, the filioque remains a major stumbling block in the relationship between the East and West.