Nothing. Nothing? Correct, Mr. Azenauer, because who'd listen to me - known to be no...

Dennis Pitt: [Meeting with Mr. Azenauer in the prison] There was some poison once, but no one recognized it. In fact, that poison was even quite... pretty-looking. So, the problem was, what to do about it? It took me some time to realize that what to do about it was very simple: nothing.
Morton Azenauer: Nothing?
Dennis Pitt: Correct, Mr. Azenauer, because who'd listen to me - known to be no good? But if that poison just stayed there, getting worse and worse, like poison always does - spreading, until even the blindest man could see, until he HAD to see...
Morton Azenauer: Go on...
Dennis Pitt: [Hesitating] Sorry... I've learned that people only pay attention to what they discover for themselves. So long...
Dennis Pitt: [Getting up] If you're ever in Winslow, see what Sue Ann is up to, will you?
Morton Azenauer: I'll keep an eye on her, Dennis.
Dennis Pitt: So long.
[Leaves the room, with Mr. Azenauer looking rather perplexed]