A Sunday school teacher was giving her class the assignment for the next week. "Next Sunday," she said, "we are going to talk about liars, and in preparation for our lesson I want you all to read the Seventeenth Chapter of Mark." The following week, at the beginning of the class meeting, the teacher said, "Now then, all of you who have prepared for the lesson by reading the Seventeenth Chapter of Mark, please step to the front of the room." About half the class rose and came forward. "The rest of you may leave," said the teacher, "these students are the ones I want to talk to. There is no Seventeenth Chapter in the Book of Mark."