It is an irony of history that so few administrative documents have survived from Byzantium, one of the most bureaucratic states of the medieval world. We know from existing documents that instructions were given to file duplicate or even triplicate copies in the offices of governmental bureaux, yet most of these originals have disappeared without trace. We possess only those documents of concern to the monastic houses which survived the onslaughts of westerners and Turks (such as the protected houses on Mount Athos) or those which found their way into ecclesiastical archives, such as the southern Italian documents to be discussed later. Everything else, including the entire imperial and governmental archives of Constantinople and the provinces has, with very minor exceptions, been lost.

But whilst much of the documentary flesh has decayed, the administrative skeleton of the middle Byzantine state has been successfully reconstructed and its guiding principles of centralization, order (taxis) and secularity established. Such principles were, in their turn, derived from two pervasive influences in Byzantine society: tradition, and its practical aspect, precedent. These two criteria were most clearly expressed in the Byzantine legal system. It was descended from the tradition of Roman jurisprudence and legislation and, in theory, provided an all-embracing system of regulating criminal and civil justice. Custom certainly played a part in Byzantine legal activity, but it was a custom either long since subsumed into codified legislation or self-consciously referred to as an external element of which the law had to take account.