This is an account of how scientific thinking has developed from the discovery of the musical scale by Pythagoras to the use today in research of genetically engineered mice. Thomas Levenson traces the history of science through the creation of both scientific and musical instruments: the organ, the still, scales, Stradivari's violins and cellos, computers, and synthesizers. What emerges is a portrait of science itself as an instrument, our single most powerful way of understanding the world. Yet perhaps the most important invention of modern science has been the power to countenance its own limitations, to find the point beyond which science can explain no more, to rediscover that science, like music, is an art.