The Empire was not intended to supersede this system of
royal government; kings no less than emperors were regarded as holding a definite
rank and office in the Christian commonwealth. No traditions of imperial
bureaucracy, except in a debased and orientalised form, were accessible to
Charles the Great. In Gaul and Italy he had subjects who lived under a corrupt
and mutilated Roman Law; but he was unacquainted with the scientific principles
of the great jurists whose writings were the highest achievements of the Roman
genius. To the best minds of the eighth century the Roman Empire appeared, not
as to an Athaulf or a Theodoric, a masterpiece of human statesmanship, but
rather a divine institution, providentially created before the birth of Christ
to school the nations for the universal domination of His Church. The model of
the Carolingian Emperors was not Augustus but Constantine the Great, the Most
Christian ruler who made it his first business to protect the Church against
heretic and heathen, to endow her with riches, to enforce her legislation.
However his relation to the Pope might be conceived, the Emperor held his
office as the first servant of the Church. What then were his practical duties?
According to some he was pledged to restore the material unity of Christendom
and to subdue all heathen peoples. This childlike ideal of his office no
emperor could put into practice. Charles the Great waged no important wars
after his coronation; he did not scruple to make peace with the Eastern Empire
or even to exchange courtesies with Haroun al Rashid, the Caliph of Bagdad. He
held, and the sanest of his counsellors agreed, that his first duty was to
protect, unite and reform the societies over which the Church already exercised
a nominal dominion. To conquer other Christian rulers was no more to be
expected of him than that he should surrender his own royal prerogative; though
it was desirable that they should do homage to him as the earthly
representative of spiritual unity.