This volume traces the development of equal-temperament and the scientific search for the perfect scale, from Pythagoras to Bach and beyond. Each chapter is devoted to a specific principal theory, critically evaluating the contributions of well and lesser-known students of the issue. Written by internationally respected authority J. Murray Barbour, the book requires minimal background of music or scientific theory. A vital text for every student of tonality, instrumental innovation, and the interaction between scientific and musical development.