He relished the society of literary men like the historian _Tacitus_. He was an intimate friend of _Pliny_ (the younger), whose correspondence while he was governor of _Bithynia_ throws much light upon the emperor's character and policy. Trajan's own manner of life was simple, and free from luxury. To the people he furnished lavishly the diversions which they coveted. He made an aggressive war against the _Dacians_ on the Danube, and constituted a new province of _Dacia_. He carried his arms into the _Parthian_ territory; and three new provinces--_Armenia, Mesopotamia_, and _Assyria_--were the fruit of his campaign in the East. In a letter to _Pliny_, he defined the policy to be pursued towards Christians, who had become very numerous in the region where _Pliny_ governed. The effect of the emperor's rescript was to place Christianity among the religions under the ban of the law. This decision was long in force, and guided the policy of future emperors towards the new faith. HADRIAN (A.D. 117-138).--Trajan was succeeded by _Hadrian_, a lover of peace,--a cultivated man, with extraordinary taste in the fine arts, and their generous patron. He was diligent and full of vigor in the transaction of public business. Although genial and affable, his temper was not so even as that of Trajan; and he was guilty of occasional acts of cruelty. He spent the larger portion of his reign in traveling through his dominions, personally attending to the wants and condition of his subjects. He constructed great works in different portions of the empire: in Rome, his Mausoleum (now the _Castle of St. Angelo_), and his grand temple of Rome and Venus. He began the wall connecting the Scottish friths. A fresh revolt broke out among the _Jews_ (A.D. 131), under a fanatic named _Bar-Cocaba_, which was suppressed in 135. _Jerusalem_ was razed to the ground; and the Jewish rites were forbidden within the new city of _Ælia Capitolina_, which the emperor founded on its site. This gave a finishing blow to the Jewish and Judaizing types of Christianity within the limits of the Church. ANTONINUS PIUS (A.D. 138-161).--_Antoninus Pius_ was the adopted son and successor of Hadrian. He was one of the noblest of princes, a man of almost blameless life. His reign was an era of peace, the golden age in the imperial history. He fostered learning, was generous without being prodigal, was firm yet patient and indulgent, and watched over the interests of his subjects with the care of a father. It is a sign of the happiness of his reign that it does not afford startling occurrences to the narrator.