Done with the last line

"Marie, let's suppose that two firemen go into a forest to put out a small fire. Afterwards, when they emerge and go over to a stream, the face of one is all smeared with black, while the other man's face is completely clean. My question is this: Which of the two will wash his face?"

"That's a silly question. The one with the dirty face, of course."

"No..."

(Excerpt from Coelho's "The Zahir")
Find the last line when you click this.