Polybius

• 1. Introduction

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  Polybius was born around 200 BC in Megalopolis, Arcadia, into a world where Greece still believed it ran its own affairs. Within two generations, Rome would control the Mediterranean. Polybius would watch it happen from the inside.

  In 167 BC, he was among a thousand Achaean nobles shipped to Rome as hostages, suspected of disloyalty after the final defeat of the Antigonid kings. He would not see home again for 17 years. Yet from that enforced exile, he produced the only substantial Hellenistic historical work to survive into the modern world: the Histories, a detailed account of Rome's rise across a span of more than a century.

  What makes Polybius unusual is not just what he wrote, but who he became. He entered Rome as a captive and left as an adviser to the man who destroyed Carthage. His ideas about constitutional balance would eventually reach Montesquieu, John Locke, and the framers of the United States Constitution. A cipher system he described would find uses in cryptography centuries after his death. And a question his work raises has never fully been resolved: can a historian who depended on Roman patronage for his survival write honestly about Roman power?

• 2. A Useful Captive

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  Polybius's father, Lycortas, had advocated neutrality during Rome's war against Perseus of Macedon in 171-168 BC. That stance drew suspicion, and when the war ended, Polybius was among those swept up in the Roman deportation of a thousand Achaean nobles. He was placed under a form of supervised internment rather than imprisonment, and his education and bearing opened doors.

  Lucius Aemilius Paullus Macedonicus, the Roman general who had just won the Third Macedonian War, took Polybius into his household and gave him responsibility for educating his sons, Fabius and Scipio Aemilianus. The relationship with Scipio Aemilianus proved transformative for both men. Polybius became his mentor and close friend, was included in the Scipionic Circle, and remained his counsellor for decades.

  When Scipio Aemilianus led Rome's campaign against Carthage in the Third Punic War, Polybius was at his side. He was present at the Sack of Carthage in 146 BC and later described what he witnessed there. After the simultaneous destruction of Corinth that same year, Polybius returned to Greece and used his Roman connections to ease the conditions imposed on the defeated Greek cities. He was then charged with organising the new forms of government in those cities, a role in which he gained considerable recognition.

  The Achaean hostages had been released in 150 BC, so technically Polybius was free before the final campaigns. But his ties to Scipio kept him at the centre of Roman power, travelling to Africa and likely to Spain for the Numantine War. He had arrived as a prisoner and stayed as an indispensable adviser.

• 3. The Histories

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  Polybius completed his Histories while residing in Rome over the succeeding years, occasionally making long journeys through Mediterranean countries to inspect historical sites firsthand. He interviewed veterans to clarify details and was given access to archival material, including treaty documents between Rome and Carthage from the First Punic War.

  The work covers the period from 264 BC to 146 BC, though it focuses mainly on the years 221-146. Books I and II introduce events in Italy and Greece before 221 BC. Books III through XXXIX track political and military affairs across the leading Mediterranean states, tracing the increasing interconnectedness, or symploke, of those states and how each contributed to Rome's dominance. Only Books I-V survive intact; a large portion of Book VI survives; the rest exist in fragments or Byzantine extracts.

  Three books break from the narrative to address broader questions. Book VI contains Polybius's theory of the anacyclosis, the cycle through which constitutions degenerate and regenerate. He presents Rome as having achieved a mixed constitution in which monarchical, aristocratic, and popular elements held each other in check, allowing Rome to avoid the cycle that had undermined the Greeks and Macedonians. Book XII examines how history should be written, criticising earlier historians including Timaeus, whose account Polybius found inaccurate and biased. Book XXXIV deals with geography and its role in a statesman's education, though it is almost entirely lost.

  Polybius concluded the Histories no later than around 118 BC; the last event mentioned appears to be the construction of the Via Domitia in southern France in that year. Writings attributed to Pseudo-Lucian record that Polybius fell from his horse while riding up from the country, fell ill, and died at the age of eighty-two.

• 4. How to Write History

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  Polybius held that historians should, where possible, only record events whose participants they were able to interview. He championed factual integrity as a professional standard, and he exemplified it by interviewing participants of the Second Punic War for the third volume of Histories, including some who had known Hannibal.

  In Book XII he defines the historian's task as three things: the analysis of documentation, the review of relevant geographical information, and the experience of politics. Political experience, in his view, was essential because it helped the historian distinguish fact from fiction. Geography mattered because you could not accurately describe a campaign or a migration without understanding the terrain.

  His own sources were varied. For events before 220 BC, he used written material: treaty documents, the history of the third-century Greek historian Phylarchus, and the Memoirs of Aratus of Sicyon, the Achaean politician. After 220 BC he continued with treaty documents and Greek and Roman historical writing, but also drew on eyewitness accounts and Macedonian court informants. He rarely named his sources, a gap that has frustrated modern scholars.

  He also included material that went well beyond political history. The Histories contain a detailed account of the machines Archimedes built to defend Syracuse against Roman attack, praising the old man and his engineering in terms described as among the highest in the work. There is also an analysis of the use of astronomy by military commanders. Both appear in the Histories rather than in separate treatises, a choice that reflects Polybius's view that a complete education for a statesman required exactly this kind of practical, applied knowledge.

• 5. The Polybius Square

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  Among the least expected contributions attributed to Polybius is a system for transmitting alphabetic messages over long distances using fire signals. Described in Book X of the Histories, the device became known as the Polybius square.

  The design is geometric in its simplicity. Letters of the alphabet are arranged left to right, top to bottom in a five-by-five grid. Five numbers are placed along the top of the square and five along the left side. Each letter is then identified by two coordinates, the column number and the row number. When encoding the 26-letter Latin alphabet, two letters, usually I and J, are combined into a single cell. When using the Greek alphabet, which has exactly one fewer letter than the 25 available cells, the final position encodes the spaces between words.

  For fire signalling, the numbers were represented by raising and lowering torches: the first number indicated the column, the second the row. Polybius considered this a significant advance over earlier fire signalling, which could only transmit prearranged messages such as an alert that the enemy had arrived. The square allowed any message to be sent, letter by letter.

  The system also lent itself to steganography and cryptographic manipulation, uses that extended its life well beyond the ancient world. Modern implementations in Western European languages such as English, Spanish, French, German, and Italian use the Roman alphabet in the same arrangement Polybius described, though Polybius himself would have used the Greek alphabet. The same grid logic that let a Greek general communicate across a valley in 150 BC still appears in modern cipher practice.

• 6. Bias and Legacy

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  Dionysius of Halicarnassus, writing in the first century BC, considered Polybius a poor stylist, and complained that no reader had the endurance to reach the end of his history. The criticism did not prevent Polybius from being widely read. Strabo quoted him extensively in the first century BC; Athenaeus mined his work in the third century AD; Livy, Plutarch, Diodorus Siculus, and Arrian all used him as a source. Cicero mentioned him.

  His emphasis on causes rather than events influenced the historian Sempronius Asellio. Much of what survives from the later books of the Histories was preserved in Byzantine anthologies; without those collections, even less would remain.

  His works reappeared in the Western world during the Italian Renaissance, first in Florence. Vernacular translations in French, German, Italian, and English appeared during the sixteenth century, expanding his readership among the learned public, though he remained, in the assessment of later scholars, a historian's historian rather than a popular one. Printings in the vernacular were modest: seven in French, five in English, five in Italian. John Dryden provided an enthusiastic preface to Sir Henry Sheers' English edition of 1693.

  John Adams counted Polybius among the most important teachers of constitutional theory. His discussion of the separation of powers, of checks and balances, and of the role of the people in government fed directly into Montesquieu's The Spirit of the Laws and John Locke's Two Treatises of Government, and through those works into the debates of the framers of the United States Constitution.

  Yet modern historians have been careful about the Histories' limits. Peter Green argues that Polybius was writing to justify the inevitability of Roman rule to a Greek audience, from a position where he could not freely express negative opinions. Ronald J. Mellor sees him as a loyal partisan of the Scipios. H. Ormerod notes his overt hostility toward the Aetolians, the Carthaginians, and the Cretans. Still, Green considers the Histories the best available source for the era they cover, and the writer of The Oxford Companion to Classical Literature of 1937 praised Polybius for his earnest devotion to truth. The Spanish philosopher Jose Ortega y Gasset called him one of the few great minds the human species has managed to produce, and described the damage to the Histories as one of the gravest losses in the Greco-Roman heritage.