Why did Benjamin Franklin fly a kite in a thunderstorm?

Can you imagine anyone flying a kite during a thunderstorm? Well, in 1752, an American, Benjamin Franklin wanted to prove that lightning was an electric spark. So, he flew a silk kite in a thunderstorm, and tied a key to the string, and was thus able to prove that lightening was indeed electricity. Luckily, Franklin himself was not burned, but all the same, the experiment was a dangerous one, and no one should try to repeat it!