Idealism often leads to downfall.

Idealism

Brutus wishes for an ideal world. He is happily married, lives in a beautiful home, and is successful according to all measures of Roman living. However, Brutus wishes for perfection in his life, and although he loves Caesar, Brutus fears Caesar is too power hungry, and might possibly destroy the Republic. Cassius understands Brutus' idealism and takes advantage of it in order to manipulate Brutus into joining the conspiracy against Caesar. At heart, it is Brutus' idealism that causes his ultimate downfall. Antony recognizes this fact when addressing Brutus' dead body at the conclusion of the play, saying "This was the noblest Roman of them all".