I do not open up the truth to one who is not eager to get knowledge, nor help out any one who is not anxious to explain himself. When I have presented one corner of a subject to any one, and he cannot from it learn the other three, I do not repeat my lesson.
不憤不啟；不悱不發。擧一隅，不以三隅反，則不復也。
Original text (Chinese)