Crossing the Rubicon What does Crossing the Rubicon mean?
When a decisive and irrevocable step has been taken.
To commit to a given course of action that permits no return is to cross the Rubicon.
Paul knew he had passed the Rubicon when he wrote the deposit check for the hall for the wedding reception. The actual Rubicon is a river in Northern Italy that flows into the Adriatic Sea. It is 15 miles (24 kilometers) long. The river is renowned because Julius Caesar prompted a three year civil war when he crossed this river in 49 B.C. to march against Pompey. Julius knew that "crossing the Rubicon" with his army in tact would be considered an act of aggression. Using the word Rubicon as a figurative boundary, limiting action was first seen in the 1600s.