A teacher was always so engrossed in the text that he never looked up at his students.
He would routinely call on a student for translation and explanation. Unaware of his own habit, he often chose the same student day after day. Out of respect, the student never pointed this out.
After being called on four days in a row, a student named Goldberg sought advice from his friends. The next day, when the teacher said, "Goldberg, translate and explain," Goldberg replied, "Goldberg is absent today."
"All right," said the teacher. "You translate and explain."