A scientist is interested in the mechanics of amphibian locomotion. So he teaches a frog to jump on command and measures the distance.

Then he cuts off one leg. "Jump, frog, jump!" Conclusion: frogs with three legs can jump only 3/4 the normal distance.

Cuts off another leg. "Jump, frog, jump!" Conclusion: frogs with two legs jump half the normal distance.

Cuts off another leg. "Jump, frog, jump!" One-quarter normal distance.

Cuts off the last leg. "Jump, frog, jump!"

Conclusion: frogs with no legs are deaf.