Polybius, the Greek historian, was born about 204 B.C. at Megalopolis in Arcadia. From his father Lycortas, one of the leading men of the Achaean League, he received valuable instruction in the science of politics and in the art of war. He was one of the 1000 noble Achaëans who, after the conquest of Macedonia in 168, were sent to Rome on the ground that the Achaëans had failed to assist the Romans against Perseus. Without any trial the Greeks were detained in an honourable captivity. Polybius was the guest of Æmilius Paulus himself, and became the close friend of his son, Scipio Æmilianus, accompanying him in his military expeditions. Polybius in his turn derived much advantage from the protection and friendship of Scipio, who gave him access to public documents, and aided him in the collection of materials for his great historical work. In 151, after sixteen years in Italy, the surviving Achaean exiles were permitted by the Roman senate to return to Greece; Polybius, however, soon rejoined Scipio, followed him in his African campaign, and was present at the destruction of Carthage in 146. But the outbreak of war between the Achaëans and Romans summoned him again to Greece, where he arrived soon after the taking of Corinth. All his influence was now exerted to procure from the conquerors favourable terms for the vanquished; and so grateful were his countrymen for his services in their behalf that they erected statues in his honour at Megalopolis and elsewhere. It must have been about this time that Polybius undertook the writing of his great historical work, the materials of which he had so long been collecting; and in furtherance of his plan he undertook several long journeys—to Asia Minor, Egypt, Upper Italy, southern France, and even Spain—where it has been supposed he witnessed the capture of Numantia by Scipio in 133. He died about 122 B.C.
His history, the design of which was to show how and why it was that all the civilised countries of the world fell under the dominion of Rome, includes the period between 220, where the history of Aratus concluded, and 146 B.C., the year when Coriuth fell, and with it the independence of Greece. Much the greater part of the work has perished. Of forty books only the first five are preserved complete; but the plan of the whole work is fully known. Of the two parts into which it was divided the first (books iii.-xxx.; the introductory books i. and ii. being a sketch of the earlier history of Rome) embraced a period of fifty-three years, commencing with the second Punic War and the Social War in Greece, and concluding with the subjugation of the kingdom of Macedonia in 168. The last ten books deal with the years 168-146. The great merits of Polybius are the care with which he collected his materials, his strong love of truth, his breadth of view, and his sound judgment, which was materially assisted by his familiarity with political and military life. He was an excellent authority on the art of war. His tone is didactic, dull, and wearisome; he is too anxious to draw consequences and deduce lessons, and has been called 'the first pragmatical historian.' His method of exposition is careless, somewhat confused, and inartistic; his style, occasionally pithy, but usually bald to a degree, belongs to the period of beginning decadence.
Of the thirty-five books which have not been preserved entire we possess merely fragments or extracts. Fragments were found by Cardinal Mai, and published as late as 1827. Valuable editions have been published by Schweighäuser (1789-95; new ed. Oxford, 1831), Bekker (1844), Dindorf (1862-68; new ed. 1882), Hultsch (1868-72; 2d ed. 1888). The portion on the history of the Achaean league has been edited by W. W. Capes, and selections (based on Hultsch) by Strachan-Davidson (1888); there is a readable English translation by E. S. Shuckburgh (1889). See Mahaffy, The Greek World under Roman Sway (1890); German works on Polybius by La Roche (1857) and Pichler (1860); and R. von Scala, Die Studien des Polybius (1891 et seq.).