Polybius, a Greek historian, born probably about 204 B. C, died about 122. His father was Lycortas of Megalopolis, one of the chief men of the Achaean league, who after the death of Philopoemen became its head. In the war between the Romans and Perseus of Macedon Polybius favored a neutral policy; but when the league decided to offer assistance to the Romans, he was appointed strategus of the cavalry, and sent to Macedonia to communicate the determination to the Roman consul. The offer was declined, but after the defeat of Perseus at Pydna, Caius Claudius and Cne-ius Dolabella came to the Peloponnesus as commissioners on the part of Rome, and by their orders 1,000 Achseans, among whom was Polybius, were carried to Italy to be tried for the crime of not having aided the Romans against the Macedonians. On their arrival in 167' they were distributed throughout the principal towns of Etruria; but through the influence of Fabius and Scipio, the sons of Pau-lus AEmilius, Polybius was permitted to dwell in their father's house at Rome, and a strong friendship sprang up between the historian and Scipio, then about 18 years old. After 17 years' detention the Roman senate granted the exiles leave to return, and Polybius accompanied the 300 survivors to their native country.

There all his efforts were employed against the party who were endeavoring to foment a war with the Romans; but his advice was disregarded, and on a statue erected to his memory was the inscription that " Hellas would have been saved if the advice of Polybius had been followed." He joined Scipio in the third Punic war, and was present at the destruction of Carthage, hastened to the Peloponnesus after the reduction of Corinth by the Romans, and did so much to mitigate the severity of the victors, that statues in his honor were erected at Megalopolis, Mantinea, Tegea, and other cities. But little is known of the rest of his life. It has been surmised that he was at the capture of Numantia by Scipio in 133, as according to Cicero he wrote a history of the Numantine war. He also wrote a life of Philopoemen, a treatise on tactics, and another on the equatorial regions. His great work is his history, which consisted of 40 books, giving an account of the growth of the Roman power from 220 B. C, where the histories of Timseus and Aratus of Sicyon left off, to 146, the year of the destruction of Corinth. The first two books comprise an introductory history of Rome from the capture of the city by the Gauls to the beginning of the second Punic war, and the first part ends with the conquest of Perseus and the downfall of Macedon. The second part reviews the Roman policy, and carries on the narration of events to the downfall of Grecian liberty.

Only five books remain entire, but fragments of the rest are still extant. The five books were first printed at Rome in 1473, in a Latin translation. In 1609 Casaubon printed at Paris an edition, in which all the fragments up to that time discovered were incorporated. The edition of Schweighauser (8 vols. 8vo, Berlin, 1789-'95) contains a Latin translation and a valuable Lexicon Polybianum. The text of this edition was reprinted at Oxford in 1823 in 5 vols. 8vo, with the lexicon. The last edition is that of Bekker (2 vols. 8vo, Berlin, 1844), who added the fragments discovered by Cardinal Mai in the Vatican library at Rome. The best English translation of Polybius is by Hampton (2 vols. 4to, 1772).