Answer:
This line is taken from Act 3, Scene 2 of "No Fear" by William Shakespeare. This was spoken by Marcus Junius Brutus. This line represents the motive and reason to kill Caesar.
Marcus exclaimed how he killed Caesar for his ambition and if he was in his place than the Plebeians would have done the same to him. Hence, this shows even after murdering Caesar he is contented and is trying to convince everyone else to think the same.
He also describes deep respect for Caesar's honor and bravery.