In 1920 Albert Einstein undertook a lengthy lecture tour of the United States to explain his new theory of relativity. The tour was so long that, towards the end, his driver mentioned that he had heard the lecture so many times that he could probably deliver it himself. Einstein suggested that he have a go, and the following night they traded places and the great man sat in the audience with his driver’s cap on, while the driver delivered the speech – with word-perfect accuracy.
Once the lecture came to an end, the Q and A started and a student in the front row threw up his hand and asked a complicated question about the mathematical structure of the space-time continuum. Without a moments hesitation, the driver pointed out Einstein in the crowd, still wearing the driver’s hat, and said “That question is so easy, that even my driver knows the answer.”