William Walrond Jackson, Ingram Bywater: The Memoir of an Oxford Scholar, 1840-1914
(Oxford: Clarendon Press, 1917), p. 60:
When he was Reader in Greek, some guests in the Common Room were anxious to know what was the difference between a Reader and a Professor. "A Reader is a man who reads, and a Professor is a man who professes to read," was the characteristic reply. I once heard C.W. Boase tell this story to Professor Skeat, prefacing it by saying that the proper term for Professor was Praelector. "Which means, I suppose," rejoined Skeat, "a man who lectures before he has read."