Two Powers, One Harmony

Symphonia, Greek for harmony or agreement, is the Byzantine Empire's own theological account of the proper relationship between imperial and ecclesiastical authority, formulated classically in the sixth century preface to a law code issued under the emperor Justinian, which describes priesthood and empire as the two greatest gifts God gave humanity, distinct in their competencies, the priesthood tending divine matters and the empire tending human affairs, yet meant to operate in concord for the good of the whole community.

Unlike the later Western medieval theory of the two swords, which developed within a persistent and often adversarial competition between pope and emperor for supremacy, symphonia describes an ideal of cooperation between offices the theory holds to be genuinely distinct in kind rather than locked in a hierarchy where one must ultimately outrank the other. In principle this meant the emperor was expected to defend Orthodoxy and support the church materially while the church prayed for and legitimated imperial rule, each respecting the other's proper sphere, a division of labor that Byzantine political theology treated as a matter of theological principle rather than a mere practical accommodation.