This book is concerned with the sport of soaring, mainly with the mathematical basis of sailplane design and operation. It does not tell the beginner how to fly, but it will give an experienced pilot some background, with historical notes showing how ideas have evolved and could develop in the future. Some of the material is taken from OSTIV (Organisation Scientifique et Technique Internationale de Vol a Viole) publications and from Technical Soaring, neither of which is readily available to the general public, including papers by the author and others. Extensive references are provided in each chapter.