Back when Einstein was giving lectures to Universities, he traveled by car. During one journey to a certain university, his driver remarked ""Dr. Einstein, I have heard you deliver that lecture over 20 times. I know it by heart and I am certain I could give it myself."" Einstein thought for a bit and replied ""Well, I'll give you the chance. They don't know me at the next University, so when we get there, I'll put on your cap, and you introduce yourself as Dr. Einstein and give the lecture"". Sure enough, at the next stop on the tour, Einstein and the driver switched places, with Einstein sitting at the back in his driver's uniform. The driver then delivered Einstein's lecture on his theory of relativity without any mistakes. When he finished and started to leave, one of the professors stopped him and asked a complex question filled with mathematical equations. The driver thought fast. He smiled and said ""the answer to that problem is so simple. I'm surprised you have to ask me. In fact, to show you just how simple it is, I'm going to ask my driver to come up here and answer your question"".