Tom, Denis, and Larry, all motorcycle enthusiasts, were debating which modern invention was most amazing. Tom lead off: “I think it’s the GPS system. It’s given us much better maps, and all we have to do is tell it where we want to go and we get complete directions.”
Denis disagreed, “Well, it works most of the time, but a couple of times, if I’d followed the GPS instructions, I’d have ridden right into the ocean. No, I think the cell phone is the most amazing invention. It’s changed our lives to a fantastic extent. Do you ever see phone booths anymore? Heck, even the plots of mystery novels have to change drastically—no more cutting the telephone lines to isolate the victim.”
Larry piped up. “Neither of you have got the right end of the stick. I think the thermos is the most amazing invention of our time.”
“Why?” asked Tom. “It doesn’t even have an on-off switch.”
“Just think about it. It keeps hot stuff hot and cold stuff cold.”
“So what?” asked Denis.
“How does it know which is which?”