Based on the "Messenger Lectures", given by the Nobel Prize-winner Feynman at Cornell and filmed by the BBC, this book explores the nature of the laws of physics (in particular, those of Newton, Maxwell and Einstein) and their relationship to mathematical formulation. Why does nature seem subject to simple mathematical laws, to what extent are there laws inherent in nature itself, and to what extent are they human creations, effective in predicting results but no more "real" than a work of art? - these are a few of the theoretical questions addressed in a rich and accessible book that sums up the essential scientific quest.