Justinian’s political theology is sometimes referred to as “dyarchy,” in which there are, or seem to be, two powers (on this ambiguity see below) ordained by God in human life, the the priestly and the imperial, sacerdotium et imperium (one cannot say the “sacred” and the “profane” for reasons which will become clear in what follows). Bishop Gelasius of Rome (492-6) had also had a doctrine of “two powers” (as outlined in a paragraph of a letter to the Emperor Anastasius, which in general discussions is usually read without reference to the context of the rest of the letter, given that, as far as I am aware, the rest of it was not available in English until last year), but Justinian configures his differently.
For Gelasius, the imperial power is ultimately subordinated to the ecclesiastical in matters that revolve around religion, and all others must refer to its judgment in such matters. Justinian had a rather different view of what constituted “human” and “divine” things. One of the more famous places in which he sets out his view is in the preface to his sixth Novella, a collection of new legislation post-dating the Codex Iustinianus, the Digest, and the Institutes.
The greatest gifts among men, made by supernal kindness, are the
priesthood and sovereignty, of which the former is devoted to things divine, and of
which the latter governs human things and has the care thereof. Both proceed from
the same beginning and are ornaments of human life. Nothing, therefore, should
receive the same attention at the hands of emperors as the dignity of priests, seeing
that the always supplicate God even on behalf of themselves (the emperors). If the
one is blameless in every respect, placing trust in God, and the other rightly and
becomingly ornaments the slate delivered to him, there will be splendid harmony
which will give to humanity whatever is for the best. Our greatest solicitude,
therefore, is as to the true dogmas relating to God as to the honor of the priests; if
they guard this, we are confident that through it God will shower much good on us;
that we shall (not only) firmly retain what we have, but further obtain what we do
not have as yet. Everything, moreover, will be carried on well and becomingly, if
only a proper beginning, pleasing to God, is made. We believe that this will be true,
if the observance of the holy canons is maintained, which the justly praised and
venerated apostles, witnesses and ministers of the word of God, delivered (to us)
and which the holy fathers maintained and explained.
The civil power here is not made to rest on the ecclesiastical power, nor the other way around: “[b]oth proceed from the same beginning.” They both seem equally ultimate. But in what follows, what Justinian actually does is, in the words of John Meyendorff, “to legislate on the marital status of the clergy, on Church property, on episcopal residence, on clergy selection and education, on obstacles to ordination, and on the legal status of the clergy” 1–most of which things we would consider “ecclesiastical.” How can this be?
For Justinian, the Church is not a separate society in political terms: it is not a polity apart. Meyendorff explains it this way: 2
These legal measures which constitute the real core of the Sixth Novella are essential for the appreciation of what the preamble really means. Obviously, “human affairs,” which the Emperor considered as being within his imperial competence, included all the legal aspects of the Church’s structure, while the “divine things” which were, according to the preamble, in the jurisdiction of the priesthood, consisted exclusively in “serving God,” i.e., in praying and in performing the sacraments. The “harmony” itself mention in the text, is not a harmony between two powers, or between two distinct societies, the Church and the State, rather, it is meant to represent internal cohesion of one single human society, for whose orderly welfare on earth the emperor alone is responsible. In Justinian’s legal thinking there is actually no place at all for the the Church as a society sui generis. The Empire and the Church are one single body of the faithful administered by a twofold, God-given hierarchy; theoretically, a duality is preserved between the imperium and the sacerdotium, but inasmuch as the priesthood’s role is to deal with divine things, it has almost no legal expression; in Justinian’s mind the law governs the entirety of human polity, and the emperor is sovereign in issuing laws. Ecclesiastical traditions and conciliar decisions are made laws by imperial decree, but they have no legal and binding existence by themselves.