Music aesthetics in late-eighteenth-century Germany has always been problematic because there was no aesthetic theory to evaluate the enormous amount of high-quality instrumental music produced by composers such as Haydn and Mozart. This book derives a practical aesthetic theory from an analysis of 1,300 reviews of instrumental music published in Germany between 1760 and 1798. The reviews document an intersection with trends in literature and philosophy, and reveal interest in criteria such as genius, the expressive power of music, and the necessity of unity, several decades earlier than has previously been supposed.