“ It is true that that which is true is true. It is false that that which is true is false. It is true that that which is false is false. It is false that that which is false is true… But if it were true that that which is true is true, it could not be false that that which is false is false. Hence, were it true that this is false, it could be false that it is true, and yet this could be false.
— Mortimer Adler, 1932. From Time, “Diagrammatics”.
