A mathematician and her husband are asked the following question: ``Suppose that you are in the basement and you want to boil water, what do you do?'' The mathematician says that she will go up to the kitchen and boil water there; her husband answers similarly. Now they are both asked the following question: ``Suppose that you are in the kitchen and you want to boil water, what do you do now?'' The husband says ``It's easier--I'll just fill the kettle and boil the water.'' The mathematician answers ``It's even easier than that--I'll go down to the basement and I already know how to solve that problem.''