This afternoon we crossed the Rubicon. ‘There’s nothing there,’ said N° 2 sprog and, of course, he was right. If it were not for the helpful sign we would not have known what we had just done. And yet this weedy trickle (if it is the right weedy trickle – archeologists and historians are divided about that) has given its name to an enduring expression in the English language. ‘To cross the Rubicon’ means ‘to pass the point of no return’, usually in pursuit of a risky enterprise. In 49 BC the Rubicon, wherever it was, marked the boundary between Cisalpine Gaul and Roman Italy. A hesitant Julius Caesar led the Thirteenth Gemina Legion over the Rubicon, deliberately breaking Roman imperium law and making conflict inevitable. According to Suetonius, Caesar declared ‘lea iacta est’ (“the die has been cast”) – another phrase that has endured in the English language. Because he won in the ensuing conflict, Caesar was never punished for his dire infraction but, as we know, history caught up with him in the end. The river, meanwhile, much reduced by industrial usage, has trickled on into a sort of parallel posterity.