What word do both Brutus and Atticus repeat and what is the effect of the repetition of these words

Antony's speech at Caesar's funeral is a masterpiece of rhetoric. He uses it to rally the people of Rome to his side against Brutus and the other conspirators who killed Caesar.

Brutus addresses the crowd just before Antony and endeavours to explain his reasons for killing Caesar. Brutus insists it was a matter of honour, that it was his duty to kill Caesar to prevent him becoming a tyrant and enslaving the people. Brutus's reasoning ...