A bunch of engineers were sitting around a conference room table discussing what each one perceived to be the most amazing invention in the history of the world. "Gotta be the wheel," said one. "It gave mankind mobility. We would not be nearly so advanced without it." "No, it has to bee the transistor," said the second one. It has revolutionized communication. We'd still be using hard wired phones without it, and we'd have to build a second house just for our computer. "Polio vaccine," says a third. "The jet engine," says a fourth. "Hey, guys," says number one. "Here comes that new arkansas red neck janitor. Let's see if he has an opinion." "Hey Bubba," says number one. "What do you think is the most amazing invention in the history of the world?" "Well, lemme see," says Bubba. He studies the question long and hard, and says, "It gotta be the thermos. It keeps hot stuff hot, and cold stuff cold, and how do it know which is which."