On Earth, God has placed no more than two powers, and as there is in Heaven but one God, so is there here one Pope and one Emperor. Divine providence has specially appointed the Roman Empire to prevent the continuance of schism in the Church.
Frederick I, Holy Roman Emperor
It is not for the people to give laws to the prince, but to obey his mandate.
Since by the ordination of God I both am called and am Emperor of the Romans, in nothing but name shall I appear to be ruler if the control of the Roman city be wrested from my hands.
