"The Cretan Liar." He might have written "This proposition is false" instead of "I am lying." The answer would be: "Very well, but which proposition do you mean?" -- "Well, this proposition." -- "I understand, but which is the proposition mentioned in it?" -- "This one." -- "Good, and which proposition does it refer to?" and so on. Thus he would be unable to explain what he means until he passes to a complete proposition.--Ludwig Wittgenstein, Zettel