(1) The Notitia Dignitatum, the great Official Gazetteer of the Empire[122], which in its existing shape appears to date from the reign of Arcadius and Honorius, early in the Fifth Century.
(2) The De Magistratibus of Joannes Lydus, composed by a civil servant of the Eastern Empire in the middle of the Sixth Century.
(3) The Variae Epistolae of Cassiodorus, the composition of which ranges from about 504 to 540.
The first of these authorities relates to the Eastern and Western Empires, the second to the Eastern alone, the third to the Western Empire as represented by the Ostrogothic Kingdom founded by Theodoric.
Much light is also thrown on the subject by the Codes of Theodosius and Justinian.
Godefroy's Commentary on the Theodosian Code, and Bethmann Hollweg's 'Gerichtsverfassung des sinkenden Römischen Reichs,' are the chief modern works which have treated of the subject.
The Officium as described in the Notitia.
We will follow the order in which the various offices are arranged by the 'Notitia,' which is most likely to correspond with that of official precedence.
In the second chapter of the 'Notitia Orientis,' after an enumeration of the five Dioceses and forty-six Provinces which are 'sub dispositione viri illustris Praefecti Praetorio per Orientem,' we have this list, 'Officium viri illustris Praefecti Praetorio Orientis:'
Princeps.
Cornicularius.
Adjutor.
Commentariensis.
Ab actis.
Numerarii.
Subadjuvae.
Cura Epistolarum.
Regerendarius.
Exceptores.
Adjutores.
Singularii.