Have you ever had a problem with a burned light? Thanks to the effort of Thomas Edison we no longer need to invent a light bulb. We just go to the store or our cupboard and pull one out and screw it in. Voila! Light!
I am sure you realize that it took Thomas Edison many, many tries before he perfected the light bulb. Someone asked him one day if he grew discouraged by his failures. He answered, I havent failed, Ive discovered one more way how not to make a light bulb.