" Pavel interrupted him. “I’ll explain what the Talmund is to you, with an example. Now listen carefully: Two chimneysweeps fall down the flue of a chimney; one comes out all covered with soot, the other comes out clean: which of the two goes to wash himself?”
Suspecting a trap, Piotr looked around, as if seeking help. Then he plucked up his courage and answered: “The one who’s dirty goes to wash.”
“Wrong,” Pavel said. “The one who’s dirty sees the other man’s face, and it’s clean, so he thinks he’s clean, too. Instead, the clean one see shte soot on the other one’s face, believes he’s dirty himself, and goes to wash. You understand?”
“I understand. That makes sense.”
“But wait; I haven’t finished the example. Now I’ll ask you a second question. Those two chimneysweeps fall a second time down the same flue, and again one is dirty and one isn’t. Which one goes to wash?”
“I told you I understand. The clean one goes to wash.”
“Wrong,” Pavel said mercilessly. “When he washed after the first fall, the clean man saw that the water in his basin didn’t get dirty, and the dirty man realized why the clean man had gone to wash. So, this time, the dirty chimneysweep went and washed.”
Piotr listened to this, with his mouth open, half in fright and half in curiosity.
“And now the third question. The pair falls down the flue a third time. Which of the two goes to wash?”
“From now on, the dirty one will go and wash,”
“Wrong again. Did you ever hear of two men falling down the same flue and one remaining clean while the other got dirty? There, that’s what the Talmund is like. "
― Primo Levi , If Not Now, When?