I had to take a few seconds to compose myself, having come quite uncomposed following his idiotic question. “Stuart”, I said, meaning to start with something he’d easily understand, “it would take a barbarian—nay, an automaton—of unprecedented unfamiliarity with the very basics of our currency system to attempt to use the same bill twice. If one didn’t know that this digital money is marked as SPENT in the Cloud database immediately following the transaction, one would hardly be able to function in society at all. I wonder, in fact, if one without such knowledge would even be able to do the more basic stuff of living, like opening doors, or tying one’s shoes, or sending one’s grandmother a nice Christmas letter listing one’s good deeds for the year. So yes, I’m quite sure that I haven’t used this particular serial-number bill before; as sure as I am of the fact that I’m not an anvil and that water doesn’t flow upward, unless you push it very hard.
From a “nonfiction tale of the future,” by Neven Morgan.