Soliloquy

In the theater, a speech by a character alone on stage, who thinks aloud and shows the audience what he does not tell the others.

In Julius Caesar

And therefore think him as a serpent's egg / Which, hatched, would, as his kind, grow mischievous, / And kill him in the shell.

Brutus is alone in the orchard, before the conspirators arrive, and thinks aloud about what he has decided against Caesar. With no one to persuade, the audience hears him assemble the argument of the "serpent's egg" that must be killed "in the shell."

Act II: The Conspiracy and the Morning of the Ides, Brutus

Cry 'Havoc!' and let slip the dogs of war

Act III: The Assassination and the Forum, Mark Antony