An even older adage (from Confucius) : "I will hold up one corner. If the student does not return, with enthusiasm, having raised the other three, the Lesson ends."
'The Master said, "I do not open the way for students who are not driven with eagerness;
I do not supply a vocabulary for students who are not trying desperately to find the language for their ideas.
If on showing students one corner they do not come back to me with the other three, I will not repeat myself."'