Randy Pausch, the Carnegie Melon computer scince professor whose last lecture inspired millions writes in his The Last Lecture (2008):

Once, about a dozen years ago, when Chris was seven years old and Laura was nine, I picked them up in my brand-new Volkswagen Cabrio convertible. “Be careful in Uncle Randy’s new car,” my sister told them. “Wipe your feet before you get in it. Don’t mess anything up. Don’t get it dirty.” I listened to her, and thought, as only a bachelor uncle can: “That’s just the sort of admonition that sets kids up for failure. Of course they’d eventually get my car dirty. Kids can’t help it.” So I made things easy. While my sister was outlining the rules, I slowly and deliberately opened a can of soda, turned it over, and poured it on the cloth seats in the back of the convertible. My message: People are more important than things. A car, even a pristine gem like my new convertible, was just a thing.