What point does Shakespeare make about the effect of political power on those who hold it? I asked this question, but the answer was off the topic a bit. I would like it answered again.
Shakespeare's Julius Caesar deals with the events surround the title character's assassination on March 15, 44 BCE.
I believe that one of Shakespeare's main points about the effects of political power on those who hold it is that the leader needs to be aware that the mere name of "leader" causes people to assume certain things about the person.
In the case of Caesar, the assumption is that Caesar was an ambitious person. Even though Caesar thrice refused the crown that Antony offered him, certain members of the Roman nobility (e.g., Casca and Cassius) believe that Caesar wanted to take it.
After Caesar's assassination, the speeches given by Brutus and Antony deal with the issue of ambition. Antony's speech and subsequent reading of Caesar's will make a strong case that Caesar was not someone who had no regard for the people of Rome.
The scene that ends Act III also seems intended to show that the application of a name or label to someone conjures up certain beliefs about that person. Consider how the angry mob attacks the poet Cinna just because he has the same name as one of the conspirators.
It is no matter, his name's Cinna; pluck but his
name out of his heart, and turn him going.
Shakespeare makes the point that political power is corrupting. Julius Caesar is ambitious, and it is this ambition, this assumption that he is the "northern star," better than any other human, that alarms his peers, such as Brutus, and puts Caesar in danger of assassination. His arrogance allows him to ignore his wife's pleas and warnings after her dream that he will be covered with blood, and he assumes, wrongly, that no one would dare touch him. As we know from other Shakespeare plays, such as Macbeth, Shakespeare's ideal ruler is "meek" (restrained), not arrogant and over-confident.
Brutus and the conspirators are also corrupted by power. They don't want Caesar to become king, because they fear it will diminish their own power. It causes them to carry out an assassination, something that in Shakespeare's plays leads to disorder.
Antony and Octavius are corrupted by power. Antony is sincerely upset by the murder of Caesar, but he is also cynical in his manipulation of the crowd and uses people like Lepidus as mere tools. He and Octavius also cut off the bequest to the people in Caesar's will. It is not a stretch to say civil war comes because Rome lacks a leader wise enough to use power well.