Mark Van Doren was my humanities teacher. One day in class, he asked a question and called on me. I wasn't paying attention and asked him to repeat the question. He then apologized to me for not making the class interesing enough for me to pay attention to his lecture.

Imagine a teacher apologizing to a student who was not paying attention to the class? What a lesson this great teacher taught me, one that I still remember over 50 years later.