The feeding of the mind with knowledge causes the mind to think. Thinking about the nature, past and the surrounding is a result of reading that leads a man to be critical. Critical thinking is a consequence of good reading. As a scholar reads they need to realize that there is reading that requires laborious work. The study of books in science and history require laborious reading.
While reading may help develop the mind it can be an activity that can turn one into a recluse. We have seen in our societies men who have buried themselves in books and have become unfit for handiwork. This does not mean that if they engage in handiwork they cannot perform, but one of the consequences of prolonged reading and scholarly activity is that one deteriorates and cannot perform heavy duties.