One of the lamentable facts of life is that nobody can have everything that he or she wants. This is due, in part, to scarce resources. Whether a teenager with a part-time job or a wealthy business-person, no single person owns all of the money in the world. Furthermore, there are only twenty-four hours in a day, and seven days in a week. Time and money are only two of the many resources that are scarce in day-to-day living.

Unfortunately, because of these limits, individuals have to make choices in using scarce resources. One can use his or her time to work, play, sleep, or pursue other options. Or, one can select some combination of possible activities. People can't spend twenty-four hours a day working, twenty-four hours a day playing, and twenty-four hours a day sleeping. People can choose to spend their salary on a nice...