The new pair of sneakers I bought feels as comfortable and as suited to walking as the best of our craftsmanship and technology can make it. But wearing it to work almost every day, I know it will last only three years at best. When you buy shoes, clothes, gadgets, and other things, you’re really not just buying a product. You’re really buying time, and along with it the promise of usefulness. In some cases—in our best moments when we happen to exhibit wisdom in purchasing—it could be an awful lot of usefulness. A steal, as we would call it. But it’s a limited usefulness nonetheless, and we know deep down that these things, even if made of tougher material than our own organic bodies, will eventually let us down. Perhaps that’s why we assign sentimental value to them. We assume things (and more so, people) will always be there. And until they are finally made of better stuff—and not only physically or chemically—we will always be surprised that they won’t.