shirt) and he could be just as mad or good-tempered as he liked, and
do what he liked, Brutus wouldn't mind him:

.... Dishonour shall be humour.
O Cassius, you are yoked with a lamb
That carries anger as the flint bears fire,
Who, much enforced, shows a hasty spark
And straight is cold again.

Whereupon Cassius weeps because he thinks Brutus is laughing at him.

Hath Cassius lived
To be but mirth and laughter to his Brutus,
When grief and blood ill-temper'd vexeth him.

Brutus: When I spoke that, I was ill-temper'd too.

Cassius: Do you confess so much? Give me your hand.

Brutus: And my heart too.

Then Cassius explains that he got his temper from his mother (as I did
mine).

Cassius: O Brutus!

Brutus: What's the matter? [Shakespeare should have added `now.']

Cassius: Have not you love enough to bear with me,
When that rash humour which my mother gave me