The expression "to cross the Rubicon" is a metaphor meaning to "to take an irrevocable step that commits one to a specific course". The phrase has its origin in Julius Caesar's decision to cross the Rubicon river in 49 BCE, bringing his troops from Gaul into Italy and starting a five-year civil war that ended the Roman Republic and began the Roman Empire. The decision sealed Caesar's political future as he was declared "dictator for life" at war's end. In the song, Dylan seems to use the refrain "And I crossed the Rubicon" in both a figurative as well as a literal sense (i.e., he is singing in the first person as Caesar). The first-person narrators of two other songs on "Rough and Rowdy Ways" also mention either identifying with or being Caesar: "My Own Version of You" ("I pick a number between one and two / And ask myself what would Julius Caesar do") and "Key West (Philosopher Pirate)" ("Got my right hand high with the thumb down").