"After my first class with him a half-century ago, I recognized that I was fortunate to have an extraordinary economist as a teacher. During that class he asked a question, and I shot up my hand and was called on to provide an answer. I still remember what he said, "That is no answer, for you are only restating the question in other words." I sat down humiliated, but I knew he was right."
That is Gary Becker writing about his first contact with his teacher M.F. Read it here.
Dick Posner's post is far more negative though, read it also.