Mysteries of State as a concept of Absolutism has its mediaeval background. It is a late offshoot of that spiritual-secular hybridism which, as a result of the infinite cross-relations between Church and State, may be found in every century of the Middle Ages and has deservedly attracted the attention of historians for many years. After A. Alföldi's fundamental studies on ceremonial and insignia of Roman emperors, Theodor Klauser discussed more recently the origin of the episcopal insignia and rights of honor, and showed very clearly how, in and after the age of Constantine the Great, various privileges of vestment and rank of the highest officers of the Late Empire were passed on to the bishops of the victorious Church. At about the same time, Percy Ernst Schramm published his compendious article on the mutual exchange of rights of honor between sacerdotium and regnum, in which he demonstrated how the imitatio imperii on the part of the spiritual power was balanced by an imitatio sacerdotii on the part of the secular power. Schramm carried his study only to the threshold of the Hohenstaufen period, and he was right to stop where he did. For the mutual borrowings of which he speaks—insignia, titles, symbols, privileges, and prerogatives—affected in the earlier Middle Ages chiefly the ruling individuals, both spiritual and secular, the crown-wearing pontiff and the mitre-wearing emperor, until finally the sacerdotium had an imperial appearance, and the regnum a clerical touch.