In the play Caesar's mixing of his public image with his private persona, is a contributing factor to his death as he thought he was "eternal". Still, in many ways, Caesar's faith that he is eternal proves valid by the end of the play: by Act 5, Scene 3, Brutus is attributing his and Cassius's misfortunes to Caesar's power reaching from beyond the grave. He was also the inspiration for Octaves and Antony and strengthening their determination. Even Octaves decision to assume the title "Caesar", Caesar's permanence is established in some respect.
His final words are most telling – he doesn't die just to avenge Caesar, but instead leaves a complicated legacy: "Caesar, now be still: I kill'd not thee with half so good a will." This incantation acknowledges the debt Brutus owes to Caesar, and it admits that Brutus sees some of his own failings too – leading him to embrace his own death. It's not that Brutus didn't willingly kill Caesar. He's as committed to his own death now as he was to Caesar's then. Brutus commits an act of self-sacrifice with no pride or self-pity. He's humble about what he's done (both good and bad) and quietly accepting of his own fate.
Shakespeare never intended the play to be historically accurate. In fact, he clearly expected the actors to appear in Elizabethan dress. Furthermore, he gives Rome the medieval invention of the mechanical clock, a notorious anachronism. However, Shakespeare's Romans share a distinct cultural heritage and society, including Roman society's implicit ideals and assumptions. When Antony calls Brutus, "the noblest of the Romans," he is referring to the specific "Roman" virtue, associated with the Republican government Brutus dies defending. The protagonists in the plot are never able to overcome the pressure of the Roman values, and thus are not completely free to invent themselves, relying instead on the cultural values provided.