What are some quotes from the play that show Brutus=self-controlled ?

Brutus decides to put the good of Rome above his self-interest and his friend. Brutus would have done quite well for himself under Caesar but he feels Rome would suffer under a dictator, I would not, Cassius; yet I love him well. act 1 sc 2

Brutus also knows he is reliable and disciplined unlike other characters,

I am not gamesome: I do lack some part
Of that quick spirit that is in Antony....act 1 sc 2.