"A clear and vivid exposition of the essential ideas and methods of the theory of relativity...can be warmly recommended especially to those who cannot spend too much time on the subject." -- Albert Einstein. Using "just enough mathematics to help and not to hinder the lay reader", Lillian Lieber provides a thorough explanation of Einstein's theory of relativity. Her delightful style, in combination with her husband's charming illustrations, makes for an interesting and accessible read about one of the greatest ideas of all times.