J. B. Bury 
History of the Later Roman Empire [PDF ebook] 
From Arcadius to Irene (395 A. D. To 800 A. D.)

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. The absolutism of Justinian extended to the ecclesiastical world, and in church as well as in state history he occupies a position of ecumenical importance. He was a sort of imperial pontiff, and this Caesaropapism, as it has been called, represents the fulfilment of the policy which Constantius tried and failed to realise.