"The first principle, when you don't know anything about the subject of a thesis, is to let the candidate talk, nodding now and then with an ambiguous smile. He thinks you know, and are counting his mistakes, and it unnerves him... the second principle of conducting an oral, ... is to pretend ignorance, and ask for explanations of very simple points. Of course your ignorance is real, but the examinee thinks you are being subtle, and that he is making an ass of himself, and this rattles him."