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. CHAPTER XXXIV THE UNKNOWABLE According to Mr. S. N. Gupta,[88] the first thing that every student of Hindu logic has to learn when he is said to begin the study of inference is that "all H is S" is not always equivalent to "No H is not S." "The latter proposition is an absurdity when S is _Kebalánvayi_, i.e. covers the whole sphere of thought and existence.... 'Knowable' and 'Nameable' are among the examples of _Kebalánvayi_ terms. If you say there is a thing not-knowable, how do you know it? If you say there is a thing not-nameable, you must point that out, i.e. somehow name it. Thus you contradict yourself." Mr. Herbert Spencer's doctrine of the "Unknowable" gives rise to some amusing thoughts. To state that all knowledge of such and such a thing is above a certain person's intelligence is not self-contradictory, but merely rude: to state that all knowledge of a certain thing is above all possible human intelligence is nonsense, in spite of its modest, platitudinous appearance. For the statement seems to show that we do know something of it, viz. that it is unknowable. To the last (1900) edition of _First Principles_ was added a "Postscript to Part I," in which the justice of this simple and well-known criticism as to the contradiction involved in speaking of an "Unknowable," which had been often made during the forty odd years in which the various editions had been on the market, was grudgingly acknowledged as follows:[89] "It is doubtless true that saying what a thing is not, is, in some measure, saying what it is;... Hence it cannot be denied that to affirm of the Ultimate Reality that it is unknowable is, in a remote way, to assert some knowledge of it, and therefore involves a contradiction."