Pope Leo the Great built his rationale for the supreme authority of the bishop of Rome on an existing tradition, yet with his additions he developed a theoretical rationale for later papal claims to absolute and supreme power in the ecclesiastical and secular realms. Previous bishops and church leaders had laid increasing stress on the unique role of the Apostle Peter as the founder of the Roman churches and episcopacy, the significance of the Roman bishop as Peter’s successor, and the apostolic significance of the city and episcopacy of Rome. Yet Leo’s rationale for the absolute control and power of the Roman bishop was founded on the ideas that Peter was still present and active in his successors, all ecclesiastical authority was mediated through him, Rome as a ecclesial monarchy was supposed to rule supreme above all churches, and Peter with his successors were to rule the universal church.
"Leo the Great on the Supremacy of the Bishop of Rome,"
Andrews University Seminary Student Journal: Vol. 1
, Article 7.
Available at: https://digitalcommons.andrews.edu/aussj/vol1/iss2/7