...but I knew that my tasks was a difficult balance between gentle encouragement and uncompromising demands.
He tells the story of a young man who met him in a book store years later and thanked him for what he taught him. Reeves concludes that...
I am fairly certain, however, that the thanks Marcus offered would not have been merited if I had created a classroom characterized by false reassurance and the absence of challenge.
-Doug Reeves The Daily Disciplines of Leadership