Brutus justifies the decision to kill his friend by literally commanding himself, out loud, to 'prevent' the hypothetical rise of Caesar. He instructs himself to ‘fashion’ the argument against Caesar, ‘think’ Caesar an unhatched snake and, finally, to ‘kill him in the shell’. Brutus shapes his own thoughts with spoken language, which is what Shakespeare asks of us.
As a director, I am not interested in a conclusive interpretation of Julius Caesar. I am not interested in spoon-feeding metaphor to the audience (Caesar = Hitler/Ceaușescu/Trump etc.). I am much more interested in exploring the ambiguities woven throughout this play. Just when you think you know a character, Shakespeare shows you another side of them. Ambiguity is Shakespeare's portal to the infinite. By asking more questions than he answers, he demands that we step up as an audience, no longer passive receivers of meaning, but active creators of it.
Julius Caesar was probably first performed in 1599, at the brand new Globe Theatre on the south bank of the Thames. Having just overseen the construction of the building, Shakespeare was in a metatheatrical mood. "All the world's a stage", a common metaphor at the time, was enshrined by Shakespeare in another 1599 play, As You Like It, and will forever be associated with his work.
In Julius Caesar, the conspirators know they are creating history. Immediately after the murder of Caesar, Cassius says:
“How many ages hence
Shall this our lofty scene be acted over
In states unborn and accents yet unknown?”
Cassius imagines himself immortalised as a saviour of Rome, presumably played by Chris Hemsworth in the movie. Of course, Shakespeare doesn't allow Cassius to bask in victory. The assassination occurs at the midpoint of the play. and Shakespeare is more interested in the fallout than in the act itself. The pre-emptive strike against Caesar creates a power vacuum that sets the cause of Roman democracy back by over a thousand years.