The first comprehensive theory of walking and running was developed by the Weber brothers in Leipzig, Germany, at the end of the nineteenth century. Their classic work is now made available to present-day medical professionals and historians in modern English translation. Wilhelm and Eduard Weber based their mathematical conclusions on anatomical studies as well as observations with the naked eye and telescope. They performed many quantitative experiments on individuals walking and running under various conditions. The Weber theory was the first serious attempt to explain these movements scientifically since Borelli's study in 1680; it preceeded the classical research of Braune and Fischer in 1895-1904 using photography. This fascinating look back into the research of the past century will captivate medical historians; the work's relevance to modern medicine will astonish bioengineers, anatomists and physiologists alike.