This is the situation that Constantine inherited upon ascending the throne. The emperor had, by the 4th century, more power than they ever had before, and that any republican or democratic state in Rome or Greece could ever have. Yet, the ancient recognition that even the mightiest of men was not outside the bounds of certain limits remained, and was even, I would argue, augmented. The major difference was that the guardianship of this unwritten, invisible law was now vested in the hands of a concrete and visible institution: the Church.
The relationship betweenthe Church and the State in the Christian Roman empire (the so-called “Byzantine” empire), is well known, and has been hottly debated through the centuries. It has also often been viewed with a certain bias, with a certain suspicion if not a downright hostility. Yet it suffices to mention the opposition to various state-sponsored (so they were viewed) heresies to show that we are far from a Church subjected to an all-powerful State. We remember all too well the Monothelite controversy, in which St. Maximus the Confessor eventually gave his life, or again the countless victims of Iconoclasm (mostly monks but also lay people) put to death by the Emperor for refusing to submit to the decree. We have in these examples a certain limitation already put upon the Emperors: they should not interfere with ecclesiastical matters, no matter how powerful they were.
But there was another domain in which the Church made its authority felt, and which would perhaps have deeper and more long-lasting consequences: the moral domain. This is primodrial because it addresses not just ecclesiastical matters, but social matters, that is, to the whole society, including (we could even say, beginning with) the emperor. We will recall St. John Chrysostom’s critics of Emperess Eudoxia’s extravagant behavior (for which he was twice exiled and died the second time). But the best and most powerful illustration of the Church’s guardianship of the new unwritten moral laws is perhaps the story of St. Ambrose, bishop of Milan, humiliating the Emperor. Let us briefly recall here that Theodosius, the emperor, had put to death 7,000 of the citizens of Thessalonica, Greece, in retaliation for the murder of the Roman governor there. On his return to Milan, the bishop barred him access to the church, holding this discourse reported by Theodoret:
“You do not reflect, it seems, O Emperor, on the guilt you have incurred by that great massacre; but now that your fury is appeased, do you not perceive the enormity of your crime? You must not be dazzled by the splendor of the purple you wear, and be led to forget the weakness of the body which it clothes. Your subjects, O Emperor, are of the same nature as yourself, and not only so, but are likewise your fellow servants; for there is one Lord and Ruler of all, and He is the maker of all creatures, whether princes or people. How would you look upon the temple of the one Lord of all? How could you lift up in prayer hands steeped in the blood of so unjust a massacre? Depart then, and do not by a second crime add to the guilt of the first.” –from Theodoret, Ecclesiastical History