of the Eastern Roman Empire. We can observe its effects in most of the works that are published on the subject. We can see that the writers do not attach clear and definite ideas to the official titles which are mentioned in their pages; they often confound distinct offices, and they confound offices with orders of rank. Schlumberger's magnificent work on Byzantine Seals may be cited in illustration; it is marred by many confusions between different officials and different departments.
It is therefore a task of urgent importance to reconstruct, so far as we can, the official organization of the later Empire at the earliest period for which we have sufficient evidence. It is true that at no period of Byzantine history have we no documents that can be remotely compared with the Codes of Theodosius and Justinian or with the Notitia Dignitatum; but we must make the best of what we have.
Now the most important document we possess, the only one that gives us anything like a full notitia of the bureaux and officials, is the Klêtorologion of Philotheos, which was compiled in the reign of Leo VI, in the year A.D. 899. It is therefore the proper starting-point for an investigation of the subject. We may say that for the institutional history of the ninth and tenth centuries it holds the same position, in relative importance, which the Notitia Dignitatum occupies for the fourth and fifth.
Once the actual organization existing in the time of Leo VI has been worked out, a further problem presents itself, namely, to trace the steps by which it developed out of the organization existing in the time of Justinian. The evidence of our literary sources shows us that in all the main essentials the later system existed in the eigth century. The transformations were effected between the end of the sixth century and the middle of the eighth, in the darkest period of Imperial history, for which we have little more than meagre secondhand chronicles and a few incidental notices in ecclesiastical documents.
In practice, however, it is impossible to separate the two investigations, namely, that of the institutions actually existing in the ninth century, and that of their history. The principal object of the present study is to determin the details of the ninth-century organization, but, as Philotheos, our main guide, only gives the names of the officials and does not indicate their functions, we are obliged to trace the offices, so far as we can, into the past, in order to discover what they were. In the case of many of the subordinate officials we have no data, and must leave their functions undetermined.
