REIGN OF CARACALLA (A.D. 211-217).--Severus conferred the empire upon his two sons, Caracalla and Geta. Caracalla murdered his brother, and then ordered Papinian, the celebrated jurist, to make a public argument in vindication of the fratricide. When that great lawyer refused, saying that "it was easier to commit such a crime than to justify it," he put him to death. Thousands fell victims to his senseless rage. Driven by remorse and fear, he fled from the capital, and wandered about the most distant provinces. At Alexandria, on account of some uncomplimentary remarks by the citizens upon his appearance, he ordered a general massacre. Finally, after a reign of six years, the monster was slain in a remote corner of Syria. [Illustration: CARACALLA.] Caracalla's sole political act of real importance was the bestowal of citizenship upon all the free inhabitants of the empire; and this he did, not to give them a just privilege, but that he might collect from them certain special taxes which only Roman citizens had to pay. Before the reign of Caracalla it was only particular classes of subjects, or the inhabitants of some particular city or province, that, as a mark of special favor, had, from time to time, been admitted to the rights of citizenship (see p. 280). By this wholesale act of Caracalla, the entire population of the empire was made Roman, at least in name and nominal privilege. "The city had become the world, or, viewed from the other side, the world had become the city" (Merivale). REIGN OF ALEXANDER SEVERUS (A.D. 222-235).--Severus restored the virtues of the Age of the Antonines. His administration was pure and energetic; but he strove in vain to resist the corrupt and downward tendencies of the times. He was assassinated, after a reign of fourteen years, by his seditious soldiers, who were angered by his efforts to reduce them to discipline. They invested with the imperial purple an obscure officer named Maximin, a Thracian peasant, whose sole recommendation for this dignity was his gigantic stature and his great strength of limbs. Rome had now sunk to the lowest possible degradation. We may pass rapidly over the next fifty years of the empire. [Illustration: TRIUMPH OF SAPOR OVER VALERIAN.]