"Professor, I have called to tell you that I don't believe in Sir
Isaac Newton's theory of gravitation!"
"Don't believe in gravitation! Suppose you jump out of that window and see whether there is any gravitation or not."
"But I don't mean that. I mean"—
"But that is all there is in the theory of gravitation; if you jump out of the window you'll fall to the ground."
"I don't mean that. What I mean is I don't believe in the Newtonian theory that gravitation goes up to the moon. It does n't extend above the air."
"Have you ever been up there to see?"
There was an embarrassing pause, during which the visitor began to look a little sheepish.
"N-no-o," he at length replied.
"Well, I have n't been there either, and until one of us can get up there to try the experiment, I don't believe we shall ever agree on the subject."
He took his leave without another word.