CRITICAL THEORY

I came across this some time ago, but to my shame cannot remember where.  Suggestions of provenance welcome.

A former head of an English department in a British university tells a true story of an old Eng Lit professor who was fed up with getting cod literary theory stuff from his students (the rest of the staff encouraged it). In one tutorial, a student was irritating him to death by insisting that, on account of the autonomy and multivalency of the text, and the irrelevancy of authorial intention, a statement in it could mean absolutely anything the reader took it to mean. 

The professor said, "Ah yes, very interesting point, what you're saying, then, is that a statement can mean one and only one thing - that thing that the author intended it to mean." 

The student said, "No of course not! I said that a text could mean anything that the reader..." 

The professor interrupted, "Yes yes, I heard you, You were saying that a text can only be interpreted one way" 

The student became indignant, "Ï didn't say that, I said exactly the opposite!" 

The professor sighed and went off to get a cup of coffee.