There was a professor who was doing experiments with a frog. He was
teaching a frog to jump. The training went on for a while and finally
when he said, Jump! the frog would jump high in the air. He thought
it was time to take some measurements and publish the results.

He started his measurements with a twine, a ruler and a knife. He
placed the frog on a wooden cutting plate and said, jump. It jumped
and he measured the height it jumped. He wrote in his observation
note book: Height jumped (with 4 legs): 14 inches. Inference: None.
Then he cut one of the legs of the frog and said jump. It jumped to
a height of 10 inches. Inference: None. Then he cut the next leg, and
measured the height jumped. Because it had only 2 legs the height
jumped was only 5 inches. The he cut one more leg and the frog now
had only one leg. The height jumped was just 1 inch with one leg.
Again the inference was none. Then he cut the last leg of the frog
and said, jump! It didnt move at all. He wrote his inference in
the note book: When all four legs are removed, frogs go deaf.