Sensing this, a good lecturer will repeat key points and connections and even invite interruptions when the audience has lost the drift. Discussion, on the other hand, is essentially a series of interruptions. If all in the group are involved, none need be left behind. It seems a happy combination, therefore, to select the Great Books, the world's best lectures, to be first read carefully and then discussed point by point - where interruptions are the rule, not the exception. This offers the prospect of the best thought being the best understood.
Discussion is intrinsically inefficient.
One can hardly expect mastery of a subject. At most, one can expect only to make a beginning. St. Thomas likens the teacher to a doctor treating the body. Likewise, the teacher only guides the student to see for himself by a light already in him. I do not mean merely that the disciple sees by his intellect, but rather that he sees in the light of those basic notions mentioned earlier - certain first principles, already formed, without which neither communication nor education could take place.