Kitchen gadgets—especially the fancy, expensive kind that are sold through the shopping channels—advertise themselves with the promise that they will change your life. Often, however, your life is changed in ways that you did not expect. You buy an electric mixer, which makes it incredibly quick and easy to make cakes. And so you feel that you ought to make cakes, whereas before you acquired the mixer, making cakes was so laborious that you were happy to buy them. In fact, therefore, the mixer has cost you time, rather than saving it.