The conquests of Justinian proved to be less enduring than his work as a lawgiver. Until his 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. These principles even influenced the Common law of England, which has been adopted by the United States. [7] The _Corpus Juris Civilis_, because of this widespread influence, is justly regarded as one of Rome's most important gifts to the world. CIVILIZING WORK OF JUSTINIAN Justinian's claim to the title of "Great" rests also on his civilizing work. He wished to restore the prosperity, as well as the provinces, of the empire. During his reign roads, bridges, and aqueducts were repaired, and commerce and agriculture were encouraged. It was at this time that two Christian missionaries brought from China the eggs of the silkworm, and introduced the manufacture of silk in Europe. As a builder Justinian gained special fame. The edifices which he caused to be raised throughout his dominions included massive fortifications on the exposed frontiers, splendid palaces, and many monasteries and churches. The most noteworthy monument to his piety is the church of Sancta Sophia [8] at Constantinople, now used as a Mohammedan mosque. By his conquests, his laws, and his buildings, Justinian revived for a time the waning glory of imperial Rome. 116. THE EMPIRE AND ITS ASIATIC FOES AFTER JUSTINIAN The Roman Empire in the East did not long remain at the pinnacle of greatness to which Justinian had raised it. His conquests, indeed, weakened rather than strengthened the empire, since now there were much more extensive frontiers to defend. Within half a century after his death it was attacked both in Europe and in Asia. The Lombards [9] soon seized Italy, and in the East the Persians renewed their contest against the Roman power. [Illustration: Map, THE ROMAN EMPIRE IN THE EAST DURING THE TENTH AND ELEVENTH CENTURIES] PERSIANS