Medieval legitimate power depended on the mutual dependence of pope and emperor.

Evidence

There was thus, from the first, a curious interdependence of pope and emperor. No one could be emperor unless crowned by the Pope in Rome; on the other hand, for some centuries, every strong emperor claimed the right to appoint or depose popes. The medieval theory of legitimate power depended upon both emperor and pope; their mutual dependence was galling to both, but for centuries inescapable. — Bertrand Russell, History of Western Philosophy, 1526

Categorization

• XREF: XREF: Traces the interdependent duality of medieval spiritual and temporal power. — connects to: Popes achieved supremacy because no Western monarch matched Byzantine imperial power. — Bertrand Russell, History of Western Philosophy, 1520; Legitimate political authority rests on an exchange of protection for obedience. — Grégoire Chamayou, A Theory of the Drone, 558; Marsilio of Padua blamed papal temporal power for Italy’s wars (+1 more)
• corroborated: 2 independent passages support this claim — Bertrand Russell, History of Western Philosophy, 1526

Broader Connections

• Legitimate political authority rests on an exchange of protection for obedience. #expands (0.35) — Grégoire Chamayou, A Theory of the Drone, 558