How we cite our quotes: In consultation with my editor, we decided (against standard practice) to go with page numbers—since The Sunset Limited is one long act and it would be unwieldy and impractical to number all the lines.
Quote #4
WHITE: Well, I've always gone my own way. Ich kann nicht anders. (109)
White's quoting Martin Luther, who said, "Here I stand. I can do nothing else." White means that he's run out of options intellectually—he can do nothing besides protesting life by embracing death.
Quote #5
BLACK: […] Meanwhile, bloodspattered spectators at the hundred and fifty-fifth street station—continued on page four—[…] who were interviewed at the scene all reported that the man's last words as he hurtled toward the oncomin commuter train were: I am right. (114)
Black pretends to read White's obituary in the paper (or the obituary of someone like him). He's implying that White's suicide is over his own intellectual rightness or sense of fairness, that he wants to prove his disdain for the world correct by killing himself.
Quote #6
BLACK: The light is all around you, cept you dont see nothing but shadow. And the shadow is you. You the one makin it. (118)
According to Black, White's ego is the thing that makes the world seem so horrible—it's the shadow cast over everything—so if he could just get that out of the way, he might be able to let a little light in.