A lecture has been well described as the process whereby the notes of the teacher become the notes of the student without passing through the mind of either.
Mortimer AdlerReading a book should be a conversation between you and the author. Presumably he knows more about the subject than you do; if not, you probably should not be bothering with his book. But understanding is a two-way operation; the learner has to question himself and question the teacher, once he understands what the teacher is saying. Marking a book is literally an expression of your differences or your agreements with the author. It is the highest respect you can pay him.
Mortimer AdlerA good book deserves an active reading. The activity of reading does not stop with the work of understanding what a book says. It must be completed by the work of criticism, the work of judging. The undemanding reader fails to satisfy this requirement, probably even more than he fails to analyze and interpret. He not only makes no effort to understand; he also dismisses a book simply by putting it aside and forgetting it. Worse than faintly praising it, he damns it by giving it no critical consideration whatever.
Mortimer Adler