In the ORIGINAL 8th Ecumenical council of 879 IV of Constantinople, (attended by all the patriarchs or their Legates, including Rome) Which was reunion council presided over by St. Photios, the following was decreed:
"Jointly sanctifying and preserving intact the venerable and divine teaching of our Lord and Savior Jesus Christ, which has been established in the bosom of our mind, with unhesitating resolve and purity of faith, as well as the sacred ordinances and canonical stipulations of his holy disciples and Apostles with an unwavering judgement, and indeed, those Seven holy and ecumenical Synods which were directed by the inspiration of the one and the same Holy Spirit and effected the [Christian] preaching, and jointly guarding with a most honest and unshakeable resolve the canonical institutions invulnerable and unfalsified, we expel those who removed themselves from the Church, and embrace and regard worthy of receiving those of the same faith or teachers of orthodoxy to whom honor and sacred respect is due as they themselves ordered. Thus, having in mind and declaring all these things, we embrace with mind and tongue (τῇ διανοίᾳ καὶ γλώσσῃ) and declare to all people with a loud voice the Horos (Rule) of the most pure faith of the Christians which has come down to us from above through the Fathers, subtracting nothing, adding nothing, falsifying nothing; for subtraction and addition, when no heresy is stirred up by the ingenious fabrications of the evil one, introduces disapprobation of those who are exempt from blame and inexcusable assault on the Fathers. As for the act of changing with falsified words the Horoi (Rules, Boundaries) of the Fathers is much worse that the previous one. Therefore, this holy and ecumenical Synod embracing whole-heartedly and declaring with divine desire and straightness of mind, and establishing and erecting on it the firm edifice of salvation, thus we think and loudly proclaim this message to all:
"I believe in One God, Father Almighty, … and in One Lord Jesus Christ, the Only-begotten Son of God… and in the Holy Spirit, the Lord … who proceeds from the Father… [the whole Creed is cited here]
Thus we think, in this confession of faith we were we baptized, through this one the word of truth proved that every heresy is broken to pieces and canceled out. We enroll as brothers and fathers and coheirs of the heavenly city those who think thus. If anyone, however, dares to rewrite and call Rule of Faith some other exposition besides that of the sacred Symbol which has been spread abroad from above by our blessed and holy Fathers even as far as ourselves, and to snatch the authority of the confession of those divine men and impose on it his own invented phrases (ἰδίαις εὑρεσιολογίαις) and put this forth as a common lesson to the faithful or to those who return from some kind of heresy, and display the audacity to falsify completely (κατακιβδηλεῦσαι ἀποθρασυνθείη) the antiquity of this sacred and venerable Horos (Rule) with illegitimate words, or additions, or subtractions, such a person should, according to the vote of the holy and Ecumenical Synods, which has been already acclaimed before us, be subjected to complete defrocking if he happens to be one of the clergymen, or be sent away with an anathema if he happens to be one of the lay people."
“Thus we think, thus we believe, into this confession were we baptized and became worthy to enter the priestly orders. We regard, therefore, as enemies of God and of the truth those who think differently as compared to this. If one dares to rewrite another Symbol besides this one, or add to it, or subtract from it, or to remove anything from it, and to display the audacity to call it a Rule, he will be condemned and thrown out of the Christian Confession. For to subtract from, or to add to, the holy and consubstantial and undivided Trinity shows that the confession we have always had to this day is imperfect. It condemns the Apostolic Tradition and the doctrine of the Fathers. If one, then having come to such a point of mindlessness as to dare do what we have said above, and set forth another Symbol and call it a Rule, or to add to or subtract from the one which has been handed down to us by the first great, holy and Ecumenical Synod of Nicaea, let him be Anathema.”
The minutes go on to record the approbation of this solemn statement by the representatives of the other Patriarchates and finally by the Emperor himself. The Emperor’s statement and signature leave no doubt of the seriousness of this theological Horos which was issued by an ecumenical Council of the Church:
“In the Name of the Father and the Son and the Holy Spirit, Basil Emperor in Christ, faithful king of the Romans, agreeing in every way with this holy and ecumenical Synod in confirmation and sealing of the holy and ecumenical Seventh Synod, in confirmation and sealing of Photios the most holy Patriarch of Constantinople and spiritual father of mine, and in rejection of all that was written or spoken against him, I have duly signed with my own hand.”