Einstein's Driver

There's a story about how Dr. Albert Einstein was traveling to Universities in his car , delivering lectures on his theory of relativity. During one journey, the driver remarked " Dr. Einstein, I have heard you deliver that lecture about 30 times. I know it by heart and bet I could give it myself."

"Well, I'll give you the chance", said the Dr. "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."

The driver delivered Einstein's lecture without any mistakes. When he finished, he started to leave, but one of the professor stopped him and asked a complex question filled with mathematical equations and formulas. The driver thought fast. "The answer to that problem is so simple," he said, " 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."