Letter CLI is the fourth confirmed letter of September 1, 457 — joining CXLVIII to Emperor Leo I, CXLIX to Basil of Antioch, and CL to Euxitheus of Thessalonica and the Illyrian bishops — making this the largest single-day cluster in the 457 correspondence that survives. Its recovery from the Ratisbon manuscript, previously unknown to the main editorial tradition, gives it independent evidentiary weight. What it shows about Leo’s governance of Constantinople’s internal affairs cannot be attributed to scribal shaping by the principal manuscript families.

The opening of the letter closes a loop that readers of this cluster will recognize. In Letter CXLVI, written July 11, Leo had directed Anatolius to keep him informed by frequent letters: frequentibus tuæ dilectionis litteris me debebis instruere. Anatolius complied; his reports provided the intelligence on which Leo acted in writing to the emperor (CXLVIII); and Leo now explicitly acknowledges that compliance, noting that Anatolius’s diligence has kept him well informed and that he has used that intelligence in his own representations before the emperor and Aspar. The relationship visible here is not collegial correspondence between two bishops of comparable standing — it is directive, execution, and acknowledgment. Leo issued the order; Anatolius carried it out; Leo confirms the fulfillment. The Archbishop of the imperial capital, at the center of Eastern political power, has been functioning as an instrument of Roman intelligence and governance throughout this campaign.

Chapter II is remarkable for its directness. Leo does not encourage Anatolius to be generally vigilant about heresy in his church — he issues a specific, named, procedurally prescribed directive. The presbyter Atticus is to be examined privately first; then, depending on the outcome, either corrected or expelled. Leo governs not only the result but the sequence: the private examination precedes any public action, and only what the examination reveals determines which of the two outcomes follows. This is not one bishop offering fraternal counsel to another about how to handle a difficult situation. It is a superior prescribing the precise procedure by which a subordinate is to manage the internal disciplinary affairs of his own clergy. The immediate jurisdiction of the Roman pontiff over the Church of Constantinople is here expressed with a specificity that leaves Anatolius’s discretion operative only at the final step — the factual determination of what the examination produces.

The target of this directive sharpens its significance considerably. Anatolius was not merely a senior bishop. He was the Archbishop of Constantinople, and by the terms of Canon 28 of Chalcedon — which Leo had formally rejected and which Anatolius had championed — he claimed a preeminence second only to Rome in the Eastern Church. Canon 28 was still actively contested at this period; Leo had never accepted it, and Anatolius knew it. Yet here Leo prescribes, step by step, the disciplinary governance of Anatolius’s own clergy in his own city. And Anatolius received it — without recorded objection. The practical relationship between Rome and Constantinople in this period was not the relationship Canon 28 claimed it should be. That Leo could write in these terms to Anatolius, and that Anatolius received it, speaks directly to the exercise of Roman primacy as an operative reality rather than a contested theory.