The Absent-minded Professor

WELL, now, where did we stop last time?" I often began my classes this way; the students would have to think back to the previous lecture, and continuity would be achieved. But on this day, I was bluffing, and the students seemed to know it. No one said anything. And I desperately needed to have them tell me what had been covered in the previous day's class, for I had no idea. I vaguely remembered going to the class, but didn't know whether I had lectured for five minutes or fifty, whether I had been on the subject, whether I had rambled. When none of the students would give me a clue, I chose a starting place at random, and feigned nonchalance. I fought down the panic I was feeling until I got home to a bottle.