The Great Gatsby, a brave voice

Could you please tell me the meaning of "brave" in this excerpt from the last chapter of The Great Gatsby?

I tried to think about Gatsby then for a moment but he was already too far away and I could only remember, without resentment, that Daisy hadn't sent a message or a flower. Dimly I heard someone murmur "Blessed are the dead that the rain falls on," and then the owl-eyed man said "Amen to that," in a brave voice.

Thank you.