Using “just enough mathematics to help and not to hinder the lay reader,” Lillian R. Lieber provides a thorough explanation of Albert 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 most celebrated ideas of all times. “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.”— “If you know high-school math, are not afraid of equations, and want to find out what Einstein really said, read Lillian Lieber’s book. She will lead you through special and general relativity, helping you at every step to understand the essential equations, including tensors, with amazing clarity and conciseness. This uniquely charming book remains as vivid as ever and even more helpful, thanks to the excellent new foreward and notes by David Derbes and Robert Jantzen.”— , author of and “Does the nature of time fascinate you? Does gravity seem a mysterious subject? Are you interested in learning just what it is that Einstein actually did that made him so famous? Then this wonderful book is just the thing. I read the original 1945 edition when I was a high-school student in the 1950s, and it had a tremendous impact on me. I predict the same experience for you, or perhaps a young friend, with this new, updated edition.”— , , and was a professor and head of the Department of Mathematics at Long Island University. She wrote a series of lighthearted (and well-respected) math books, many of them illustrated by her husband, . teaches physics at the University of Chicago Laboratory Schools. is a professor of mathematics at Villanova University.