The great theoretical physicist & Nobel Prize winnder, Richard Feynman, left an indelible imprint on scientific thought. On 14 March 1964 he delivered a remarkable lecture which, until now, was believed to be lost. His lecture was about a single fact, though by no means a small one. When a planet or a comet or any other body arcs through space under the influence of gravity, it traces out one of a very special set of mathematical curves, known as the conic sections. But why does nature choose to describe those, & only those, elegant geometrical constructions ? In this book Feynman's lost lecture has been reconstructed & explained in meticulous, accessible detail, together with a history of ideas of the planets' motions. It can be enjoyed by the specialist & non-specialist alike & provides us all with an invaluable insight into the mind of one of this century's greatest scientists.