Filioque

===Photian controversy===
Around 860 the controversy over the {{lang|la|Filioque}} broke out in the course of the disputes between Patriarch [[Photios I of Constantinople|Photius of Constantinople]] and Patriarch [[Ignatius of Constantinople]]. In 867 Photius was Patriarch of Constantinople and issued an ''Encyclical to the Eastern Patriarchs'', and called a council in Constantinople in which he charged the Western Church with [[heresy]] and schism because of differences in practices, in particular for the {{lang|la|Filioque}} and the authority of the Papacy.{{sfn|Schaff|1885|loc=[http://www.ccel.org/ccel/schaff/hcc4.i.v.iv.html §70]}} This moved the issue from jurisdiction and custom to one of dogma. This council declared Pope Nicholas anathema, excommunicated and deposed.{{sfn|ODCC|2005|loc="Photius"}}

Photius excluded not only "and the Son" but also "through the Son" with regard to the eternal procession of the Holy Spirit: for him "through the Son" applied only to the temporal mission of the Holy Spirit (the sending in time).{{sfn|Chadwick|2003|p=154|ps=: "Photius could concede that the Spirit proceeds through the Son in his temporal mission in the created order but not in his actual eternal being"}}{{sfn|Schaff|1885|loc=[http://www.ccel.org/ccel/schaff/hcc4.i.xi.iii.html §108 II]|ps=: "Photius and the later Eastern controversialists dropped or rejected the ''per Filium'', as being nearly equivalent to ''ex Filio'' or ''Filioque'', or understood it as being applicable only to the mission of the Spirit, and emphasized the exclusiveness of the procession from the Father"}}{{sfn|Meyendorff|1986|loc=[http://www.myriobiblos.gr/texts/english/Meyendorff_12.html §2]|ps=: "[[Nikephoros Blemmydes|Blemmydes]] {{interp|...&nbsp;was}} committed to {{interp|...}} church unity and defended the idea that the image of the Spirit's procession 'through the Son', can serve as a bridge between the two theologies. {{interp|...&nbsp;He}} collected patristic texts using the formula 'through the Son' and attacked those Greeks who out of anti-Latin zeal, were refusing to give it enough importance. In general, and already since Photius, the Greek position consisted in distinguishing the ''eternal'' procession of the Son from the Father, and the ''sending'' of the Spirit ''in time'' through the Son and by the Son. This distinction between the eternal processions and temporal manifestations was among the Byzantines the standard explanation for the numerous New Testament passages, where Christ is described as 'giving' and 'sending' the Spirit, and where the Spirit is spoken of as the 'Spirit of the Son'. In his letters {{interp|...}} Blemmydes {{interp|...}} avoided the distinction between eternity and time: the patristic formula 'through the Son' reflected both the eternal relationships of the divine Persons and the level of the 'economy' in time."}} He maintained that the eternal procession of the Holy Spirit is "from the Father {{em|alone}}".{{refn|Photius, ''Epistula 2'' (PG 102:721–741).}}{{Verify quote|date=December 2015}} This phrase was verbally a novelty,{{sfn|Papadakis|1997|p=113}}{{sfn|Lossky|2003|p=168}} however, Eastern Orthodox theologians generally hold that in substance the phrase is only a reaffirmation of traditional teaching.{{sfn|Papadakis|1997|p=113}}{{sfn|Lossky|2003|p=168}} [[Sergei Bulgakov]], on the other hand, declared that Photius's doctrine itself "represents a sort of novelty for the Eastern church".{{sfn|Bulgakov|2004|p=144}} Bulgakov writes: "The Cappadocians expressed only one idea: the monarchy of the Father and, consequently, the procession of the Holy Spirit precisely from the Father. They never imparted to this idea, however, the exclusiveness that it acquired in the epoch of the Filioque disputes after Photius, in the sense of {{transliteration|grc|ek monou tou Patros}} (from the Father alone)";{{sfn|Bulgakov|2004|p=80}} Nichols summarized that, "Bulgakov finds it amazing that with all his erudition Photius did not see that the 'through the Spirit' of Damascene and others constituted a different theology from his own, just as it is almost incomprehensible to find him trying to range the Western Fathers and popes on his Monopatrist side."{{sfn|Nichols|2005|p=157}}

Photius's importance endured in regard to relations between East and West. He is recognized as a saint by the Eastern Orthodox Church and his line of criticism has often been echoed later, making reconciliation between East and West difficult.

At least three councils – [[Council of Constantinople (867)]], [[Fourth Council of Constantinople (Roman Catholic)]] (869), and [[Fourth Council of Constantinople (Eastern Orthodox)]] (879) – were held in Constantinople over the actions of Emperor [[Michael III]] in deposing Ignatius and replacing him with Photius. The Council of Constantinople (867) was convened by Photius to address the question of Papal Supremacy over all of the churches and their patriarchs and the use of the {{lang|la|Filioque}}.{{sfn|Fortescue|1908|pp=147–148}}{{sfn|Louth|2007|p=171}}<ref>{{cite book|last=Tougher|first=Shaun|year=1997|title=The reign of Leo VI (886–912): politics and people|series=Medieval Mediterranean|volume=15|location=Leiden [u.a.]|publisher=Brill|isbn=9789004108110|page=69|url=https://books.google.com/books?id=iPquae5A4zIC&pg=PA69}}</ref>{{sfn|Siecienski|2010|p=103}}

The council of 867 was followed by the Fourth Council of Constantinople (Roman Catholic), in 869, which reversed the previous council and was promulgated by [[Diocese of Rome|Rome]]. The Fourth Council of Constantinople (Eastern Orthodox), in 879, restored Photius to his see. It was attended by Western legates Cardinal Peter of St Chrysogonus, Paul Bishop of Ancona and Eugene Bishop of Ostia who approved its canons, but it is unclear whether it was ever promulgated by Rome.{{sfn|Fortescue|1911}}