Thucydides tells us that he was a "young man" at the outbreak of hostilities between Athens and Sparta in 431 B.C.E. Between 430 and 427 he caught the plague (whose devastating impact on the Athenians is described in Book 2 of the History), but recovered. And in 424 he was serving as one of the city's ten strategoi, or generals, charged with safe-guarding Athenian interests in the northern Aegean. But he could not save the coastal city of Amphipolis from the attack of the Spartan general Brasidas, as a result of which Thucydides was exiled from Athens for twenty years. Where Thucydides lived during this time is not known for certain, though it is likely that he spent at least part of it at his estate on the mainland opposite the island of Thasos. And he probably traveled, gathering material for his History. Thucydides returned to Athens in 404, and died a few years later, around 400.
Thucydides began to research and write his History shortly after the war started, and worked on it until his death; indeed, the work was left unfinished. A fanciful tradition recounts that Thucydides' daughter wrote Book 8; still, she may have had something to do with the work's preser-vation. Also, the present-day division into eight books is not original, but the work of a later editor. But if the History remains unfinished and lacks revision in places, it is a coherent whole whose immediate purpose is clear: to recount the war between Athens and Sparta--its causes and how it brought in its wake a "convulsion" greater than anything yet known.
The first of the "scientific" historians, Thucydides strove for accu-racy, which he achieved by having been present at the events he describes or by having interviewed reliable witnesses. He also consulted docu-mentary material when possible. Where complete certainty was lacking, Thucydides recreated events and devised speeches to accord with prob-ability, that is, with what is most likely to have happened, in order to arrive as near as possible to the truth. Thucydides' stress on etiology linked him with the medical and scientific writers. His carefully wrought speeches and vivid characterization put him with the dramatists. This antinomy, almost, between the detached observer and the impassioned poet would help explain the corresponding differences between Thucydides' manner of writing, which ranged from the plainly narrative to the highly oratorical.
Thus did Thucydides wed accuracy and historical probability with dramatic power. Part of the drama, the tragedy, really, of the History was to show how Athens' downfall resulted from a failure of leadership fol-lowing the death of Pericles, Athens' "first citizen" and leader whom Thucydides greatly admired despite the fact that Pericles represented the "democratic" forces while Thucycides' background would link him with the oligarchs. The leaders after Pericles (who died of the plague) committed acts of barbarity and cruelty, e.g., the destruction of the neu-tral Melians in Book 5. The final disaster for Athens came with the failed Sicilian expedition, described in Books 7 and 8, which illustrates Athens' ruthless expansionism and overreaching ambition. But atrocities occurred among the Spartans as well (e.g., the Spartan siege of Plataea in Book 3). Such episodes on both sides gave Thucydides the clinician and the tragic poet the opportunity to assess the pathology of human behavior and how war unchains the most brutal passions.
Control of human passions, noble or otherwise, lay with the human agents themselves. Unlike Herodotus, who believed that humankind's destiny was governed by divine forces, Thucydides looked toward nat-ural phenomena to find the underlying causes. But human intelligence has its limits, beyond which lies the unseen.
Thucydides realized that the loftiness and the severity of his ideals would prevent his work from becoming a mere showpiece or entertain-ment. Rather, his aim was to create a "possession for all time." Behind this vaunt lay Thucydides' deeper purpose: to impart a reliable picture of human behavior and motivations, and to display truly the causes of events.