A cup rattles, three small cubes of bone or ivory spill across a wooden board, and for one held breath the whole room leans in. A soldier's monthly pay, a merchant's profit, and occasionally a man's own freedom was riding on which faces land upward. That scene played out countless times a day throughout the ancient world, in army camps on the frozen Rhine, in the back rooms of Pompeian wine shops, in the tiled gaming chambers of senatorial villas, and in the palace itself, where more than one emperor kept a set close at hand.

Dice were everywhere in antiquity, and that ubiquity is exactly what makes them worthy of historical interest thousands of years later. Kings and slaves cast the same bones, a game that cost a laborer a copper coin could cost a nobleman an estate, and both men prayed to the same gods for a lucky throw. Few objects cut so cleanly across the social lines the ancient world drew between people, and few pastimes left such a broad trail through the sources, from the letters of emperors and the verses of poets to the sermons of moralists, the statutes of lawmakers, and the painted walls of taverns where the players are depicted arguing over a bad roll.

There is a paradox at the heart of the story. Romans threw dice constantly, and yet for most of Rome’s history, the law forbade it. Gambling with dice was formally banned outside the winter festival of the Saturnalia, yet the ban was ignored so completely that the emperors who signed such laws were themselves famous for breaking them. Of course, the story of dice and games of chance began long before Rome, in the knucklebones of a sheep and the tall tales the Greeks told about who first thought to throw them.