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  George Boole (1815-1864) was a college professor who
   never graduated from college. He was born into an English
   family so poor that they could only afford a few years of
   schooling for their son. But George made good use of
   those years. One of his teachers, Mr. DeKalb, was a well-
   meaning man who sometime learned more from the students than
   they learned from him. In an effort to teach the idea of
   proof Mr. DeKalb asked the class to consider the faces of
   a polyhedron: "If a polyhedron can rest on a face then we
   call that face stable. But if, by the force of gravity,
   the polyhedron rolls over onto another face, then the
   first face is unstable. Now I ask you to consider the
   possibility of a polyhedron with all unstable faces. Can
   such a polyhedron exist?"

      The next day Boole returned with the answer that such
   a polyhedron could not exist.

      "And what is your proof?" asked Mr. DeKalb.

      "I have asked my father and he has asked his friends,
   many of whom are very intelligent. And they all agree
   that such a solid is impossible."

      "Not a proof!" shouted Mr. DeKalb. "You have based
   your conclusion on a vote, on an opinion poll. Neither
   science nor mathematics proceeds in this way."

      "But my father is very clever, and his friends are
   like him. They spend nearly every Sunday afternoon
   discussing things of the mind. And they all agreed that
   such a thing is impossible, inconceivable to them. I
   accept their conclusion."

      "Not a proof. That is not the way science and
   mathematics work."

      "Well then, what is the proof?" asked Boole.

      "The reason that the polyhedron can't exist is that
   if all faces were unstable, the object would be a
   perpetual motion machine. And perpetual motion machines
   don't exist."

      "But how do you know that?" asked Boole.

      "By the law of conservation of energy. You can't get
   more energy out of a system than you put into it."

      "Well, what is your proof of this law?" queried Boole.

      "It has no proof. Its an axiom. And that is how science
    and mathematics are done. All proofs are based on a few
    accepted facts."

      "But why would anybody accept the law of conservation
    of energy?" Boole asked.

   " Please Mr Boole, the experts tell us these things."

                             The End