When Jesus was born, the Roman Empire extended from the Euphrates to the Atlantic, and from the African desert to the Danube, Rhine, and Weser. It formed a wide fringe around the Mediterranean Sea, included the best parts of three continents, and had a population of 100,000,000.[40:1] The Empire was called "the world." Roman law was predominant throughout the provinces as well as at Rome, but local usages were tolerated. Citizenship had become so widely extended that the different peoples began to feel themselves a single race, bound together by one Emperor, one government, and one code of laws. The era of the boyhood of Jesus was one of comparative peace, since there was no important war after the naval battle of Actium (31 B.C.).[41:1] Hence the industries of the Empire prospered greatly. Across the Mediterranean as the great highway, up and down the rivers, and along the incomparable Roman roads, an enormous trade was carried on between the colonies and the capital, Rome.[41:2] Factories thrived in every direction and commerce flourished. Showers of wealth fairly fell upon the Eternal City. The trade of the Empire was carried on in Latin, the official language of the Empire for law and war. Greek was also a universal tongue, but used more especially for art, science, philosophy, education, and religion.[41:3] Cicero complained: "Greek is read in almost all nations. Latin is confined by its own natural boundaries." Hebrew and other tongues were sectional. The literature of the opening century of the Christian era, however, was largely in Latin,[41:4] which had been fertilised by Greek culture. Education had made far greater progress in this old world than is generally thought. Judea,[41:5] Greece,[41:6] and Rome[42:1] had excellent systems of education, though differing much in purpose and in subjects studied. Pronounced schools of philosophy grew up. Art, comparatively little developed among the Jews, culminated with the Greeks, and from them was transplanted to Rome. Travel, always liberalising and educational, was widespread among scholars, tradesmen, soldiers, and public officials. All these factors had produced a superior intelligence and general culture throughout the Empire.