There is no teaching without the student thinking along and questioning the professor. Teaching is not primarily information transmission, rather it's the engagement of active minds in the process of investigation and reflection. The professor can mentor the process, but it is impossible for the professor to sustain it alone. It takes two to tango. Increasingly, I've come to realize just how essential it is for the student to question and think during class.
Vegetative presence is largely a waste of time.
Perhaps students would be more excited about learning if they realized how special we educated few are in the course of human history and just how valuable the mind and talents of each person truly are, especially their own. But the insight remains legitimate. It's my hope that those students reading my little diversion will think just a bit on my admonishment. The greatest project in life is to develop your own talents and abilities. But above all, students need to value themselves.