ABSTRACT
The theorems of cardinal arithmetic are frequently used in ordinary conversation. What is known as the Schröder-Bernstein theorem was used, long before Bernstein or Schröder, by Edward Thurlow, afterward the law-lord Lord Thurlow, when an undergraduate of Caius College, Cambridge. Thurlow was rebuked for idleness by the Master, who said to him: “Whenever I look out of the window, Mr. Thurlow, I see you crossing the Court.” The provost thus asserted a one-one correspondence between the class A of his acts of looking out of the window and a part of the class B of Thurlow’s acts of crossing the Court. Thurlow asserted in reply a one-one correspondence between B and a part of A: “Whenever I cross the Court I see you looking out of the window.” The Schröder-Bernstein theorem, then, allows us to conclude that there is a one-one correspondence between the classes A and B. That A and B were finite classes is not the fault of the Master or Thurlow; nor is it relevant logically.
