"There are three men in a bar, a doctor, a lawyer, and a mathematician ... and they are discussing whether it's better to have a wife or a ... mistress. The doctor says, "It's much better to have a wife because you work all day, you come home at the end of the day, you want to have a steady, settled family life." And the lawyer says, "No, no, no, no, no. It's much better to have a mistress because maybe for the first 5, 10, 20, 30 years you'd like to have a steady family life, but if you change your mind, it gets incredibly complicated, so it's much, much better to have a mistress." And they're going back and forth, they can't agree, so they turn to the mathematician. "What do you think?" And the mathematician says, "It's better to have a wife and a mistress. And the reason is, your wife will be afraid to ask if you are spending time with your mistress and your mistress will know that of course you have to spend some time with your wife. Which means you can spend your time doing mathematics!"
Source: Joel Cohen, http://bigthink.com/ideas/19346
