Once upon a time, during a large and international conference of the world's leading philosophers, an angel miraculously appeared and said, "I come to you as a messenger from God. You will be permitted to ask any one question you want - but only one! - and I will answer that question truthfully. What would you like to ask?" The philosophers were understandably excited, and immediately began a discussion of what would be the best question to ask. But it quickly (...) became obvious that they needed more time to discuss the matter, so they asked the angel if he could get back to them. The angel was obliging, and said that he would return at the same time the next day. "But be prepared then," he warned them, "for you will only get this one chance." All of the philosophers gathered at the convention worked at a frenzied pace for the next twenty-four hours, proposing and weighing the merits of various questions. Other philosophers from around the world became involved as well, faxing and emailing their suggestions. Some were in favor of asking the kind of practical question that lots of people might like to know the answer to, such as this one: Q1 Is it better to check your oil when the car is hot or when it is cold? But others said they should not squander this rare opportunity, which gave them a chance to learn something about a truly important and intrinsically interesting topic, and after some discussion it was generally agreed that this was right. (shrink)