The Roman Empire in the East, though threatened by enemies from without and weakened by civil conflicts from within, endured for more than a thousand years. Until the middle of the fifteenth century it preserved the name, the civilization, and some part of the dominions, of ancient Rome.

The long life of the Roman Empire in the East is one of the marvels of history. Its great and constant vitality appears the more remarkable, when one considers that it had no easily defensible frontiers, contained many different races with little in common, and on all sides faced hostile states.

The changing fortunes of the empire during the Middle Ages are reflected in some of the names by which it is often known. The term “Greek Empire” expresses the fact that the state became more and more Greek in character, owing to the loss, first of the western provinces in the fifth century, and then of Syria and Egypt in the seventh century.

Another term– “Byzantine Empire”—appropriately describes the condition of the state in still later times, when its possessions were reduced to Constantinople (ancient Byzantium) and the territory in the neighborhood of that city. But through all this period the rulers at Constantinople regarded themselves as the true successors of Augustus, Diocletian, and Constantine.

Until Justinian’s reign the sources of Roman law, including the legislation of the popular assemblies, the decrees of the Senate, the edicts of the of Roman praetors and emperors, and the decisions of learned lawyers, had never been completely collected and arranged in scientific form. Justinian appointed a commission of legal scholars to perform this task.

The result of their labors, in which the emperor himself assisted, was the publication of the Corpus Juris Civilis, the “Body of Civil Law.” Under this form the Roman principles of jurisprudence have become the foundation of the legal systems of modern Italy, Spain, France, Germany, and other European countries.