When Brutus joined the conspiracy against Caesar, he did it solely for the good of Rome. Unlike all the other men, Brutus justified his motive for murder: Brutus feared that Caesar would alter his attitude when he was crowned emperor: "He would be crown'd/ How that might change his nature..." (II,i,12-13). Brutus was afraid of the possibility of a negative change in Caesar that could doom Rome.
Cassius formed the conspiracy with motives based solely on envy, and he believed that Caesar was not going to be a good enough ruler. He says: "...it doth amaze me A man of such feeble temper should So get the start of the majestic world And bear the palm alone." (I,ii,128-31) Cassius also thought that he was also much stronger than Caesar. Cassius says: "...Caesar said to me, `Dearest thou, Cassius, now Leap in with me into this angry flood, And swim to yonder point?' Upon the word Accoutred as I was, I plunged in and bade him follow; so indeed he did. The torrent roared...but ere we could arrive the point proposed, Caesar cried, `Help me Cassius, or I sink.'...So from the waves of Tiber Did I the tired Caesar: and this man Is now become a god and Cassius is A wretched creature...". (I,ii,102-117) Cassius had to save Caesar from the river, which draws him to the conclusion that he deserves recognition for his strength over Caesar. One of Brutus' flaws is that he is not very bright. He is an idealist; he doesn't think about the consequences of Caesar's murder. For example, when Cassius presented the idea of swearing an oath of secrecy within the conspiracy, Brutus assumes that all of the other men were as noble as he and would not tell