III. The ancient precedents are to be maintained throughout.
Accordingly, both in the rule of Faith and in the observance of discipline, let the standard of antiquity be maintained throughout, and display, beloved, the firmness of a prudent ruler, that the church of Alexandria may get the benefit of my earnest resistance to the unprincipled ambition of certain people in maintaining its ancient privileges, and of my determination that all metropolitans should retain their dignity undiminished, as you will ascertain from the tenor of my letters, which I have addressed, whether to the holy Synod or to the most Christian Emperor, or to the Bishop of Constantinople; for you will perceive that I have made it my special care to allow no deviation from the rule of Faith in the Lord's churches, nor any diminution of their privileges through any individual's unscrupulousness.
And as this is so, hold fast, brother, to the custom of your predecessors, and keep due authority over your comprovincial bishops, who by ancient constitution are subject to the See of Alexandria; so that they resist not ecclesiastical usage, and refuse not to meet together under your presidency, either at fixed times or when any reasonable cause demands it: and that if anything has to be discussed in a general meeting which will be to the benefit of the Church, when the brethren have thus met together, they may unanimously come to some resolution thereupon.
For there is nothing which ought to recall them from this obedience, seeing that both for faith and conduct we have such good knowledge of you, brother, that we will not allow you to lose any of your predecessor's authority, nor to be slighted with impunity. Dated March 10th, in the consulship of the illustrious Aetius and Studius (454).
Source: Letters (New Advent)