This book presents a series of classic lectures, delivered in 1960 and recorded for the BBC. This is Feynman's unique take on the problems and puzzles that lie at the heart of physical theory - with Newton's Law of Gravitation; on whether time can ever go backwards; on maths as the supreme language of nature. Demonstrates Feynman's knack of finding the right everyday illustration to bring out the essence of a complicated principle - eg brilliant analogy between the law of conservation energy and the problem of drying yourself with wet towels. 'Feynman's style inspired a generation of scientists. This volume remains the best record I know of his exhilarating vision' - Paul Davies.