Brave is Mad

Quote from The White Tiger: the he in the second line is 'supposedly brave and mad'.

"What are you doing here?"
"Voting," he shouted back. "Isn't it the election today?"
I cannot confirm what happened next, even though I was only a few feet behind him. A big crowd had gathered to watch him from a distance, but when the policeman charged at us, we turned and ran in a stampede. So I never saw what they did to that brave, mad man.
I heard about it the next day, while pretending to scratch a dirty spot out of a tabletop. Vijay and a policeman had knocked the rickshaw-puller down, and they had begun beating him; they hit him with their sticks, and when he thrashed at them they kicked him. They took turns. Vijay hit him and the policeman stamped on his face and then Vijay did it again. And after a while the body of the rickshaw-puller stopped wriggling and fighting back, but they kept stamping on him, until he had been stamped back into the earth.
"

Now being brave, is often being impractical. Which is, being mad. Being mad is basically showing off your eccentricity. It takes courage. So being mad is being brave.

Hence,
Being brave <=> Being mad.