Ludwig Boltzmann arguably played the key role in establishing that submicroscopic structures underlie the ordinary world. He had a tremendous impact on late 19th-century and early 20th-century physics, and he anticipated many contemporary ideas, including Kuhn's theory of scientific revolutions and recent theories of knowledge based on Darwinian principles. This book is the first accessible biography of this important figure. Without relying on equations, it provides a deep look at the full range of his scientific and philosophical ideas, discussing both their original context and their relevance today. The book also gives a concise portrait of Boltzmann's life, which, despite his successes, ended tragically in suicide. Drawing on recent research related to some of Boltzmann's more controversial ideas, this book offers fascinating insights into the birth of modern physics.