Calendars are the bones of history. They fortify the memory of individuals and societies, and they suggest explanations for documented events. Without them there would be no structure to what happens apart from sequential order. All calendars depend on astronomy and the cycles of the seasons, but fixing a starting date is unavoidable.
The history of the Greek and Roman world is full of different calendars, often called eras, which served states and rulers as a means of commemorating them for good or ill. Eras furnished a commonly accepted chronology, often with more than local recognition. The Romans dated their republic from the foundation of the city (ab urbe condita), which had a traditional but fictitious date of 753 BCE, supported by the first-century BCE scholar M. Terentius Varro. The Athenians dated by the year of individual magistrates known as archons; the Jews used traumatic events such as the Babylonian exile. Many individual cities had their own calendars, which began with the tenure of specific magistrates or priests and restarted at the beginning of a new tenure.
An event could thereby be dated in many ways. In trying to locate the precise time of the outbreak of the Peloponnesian War, Thucydides, with his characteristic thoroughness, offers a bouquet of dates—the fifteenth year after the conquest of Euboea, the forty-eighth year of a priesthood at Argos, the year of Pythodorus’s archonship at Athens, and six months after the battle of Potidaea.
So it is hardly surprising that the first king of the Seleucid monarchy in Syria started a new calendar for his empire from the time he moved into Babylon in 311 BCE. He did not actually set up this new calendar until he had eliminated all his rivals in 305, but he retrojected his first year by six years, so that his new era began in 311. This move to establish his claim from the earliest moment of his uncontested authority in the region might easily be understood as yet another attempt to hitch a calendar to the reign of a king. But through a dense and wide-ranging study, grounded in the languages of the region (Akkadian and Greek), Paul Kosmin has brilliantly demonstrated in his new book, Time and Its Adversaries in the Seleucid Empire, that Seleucus did much more than that.
Kosmin has seen, as no one before him, the chronology and consequences of the chaos that followed the death of Alexander the Great in 323 BCE. Historians have, of…
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