Object: A lantern

Good morning, boys and girls. How many of you have ever been to a doctor? We go to the doctor when we are sick, don't we? Or sometimes, we go to the doctor to get a shot to keep us from getting sick.

I understand that in ancient China doctors were paid when their patients were kept well, not when they were sick. In fact, because they believed it was the doctor's job to prevent disease, Chinese doctors often paid the patient if the patient lost his health. That's a novel idea. Furt…