Alea iacta est

The Latin sentence Alea iacta est (usually translated as ‘The die is cast’) is appropriately said when a person has committed themselves irrevocably to a particular course of action: whether the action will achieve its objective, whether it will succeed or fail, may be unclear, but the decision to act has been taken and there is now no going back. The type of situation in which this metaphorical expression is used mirrors the type of situation in which the expression has its origin, viz., the throwing of a die in a game of chance: once the die has been thrown, it cannot be brought back, but which of its sides will be uppermost when it falls (whether the number it shows will please the player) is uncertain.

According to the Roman historian Suetonius, Alea iacta est (or a close variant of it – see below) was said by Julius Caesar when, on 10th January 49 BCE, he led one of his legions across the river Rubicon in northern Italy. The Rubicon marked the southern boundary of the province of Cisalpine Gaul, of which Caesar was then governor, and without the permission of the Senate in Rome, which Caesar did not have, it was illegal for a governor to take an army outside his province. So, in crossing the Rubicon, Caesar was acting in defiance of the Senate and making it inevitable that there would be civil war between himself and his great rival Pompey, the general supported by the senatorial party.

What did Caesar actually say when he crossed the Rubicon? Although Alea iacta est is the form in which Caesar’s words are commonly quoted today, Suetonius quotes them, with a different word order, as Iacta alea est – which by putting the past participle iacta first gives it particular emphasis, stressing that the die is indeed cast. Rather differently, according to the Greek historian Plutarch’s account, Caesar spoke in Greek and said ἀνερρίφθω κύβος (anerríphthō kubos, ‘Let a die have been cast’), i.e., he used a iussive rather than an indicative form of the verb. (For another, even more significant occasion on which Caesar is said to have spoken in Greek, see Et tu, Brute?.)

See also Crossing the Rubicon.