Nonlinear business cycle theory, an innovative dynamic theory of why fluctuations happen, thrived in the 1940s, until the Keynesian base upon which it was structured began to give way to a more neoclassical approach to economics. Largely forgotten for half a century, the theory has been resurrected recently, as research on complex, nonlinear dynamics from the worlds of physics, biology, and sociology have made their way into economics, and as the debate over what is known as "real business cycle theory" heats up. Vela Velupillai's book is a history of the boom, bust, and rebirth of an idea; how theories fall in and out of fashion in the field of economics. It is a story of the personalities which drive economic thought, of the alliances and biases that define the orthodoxy of the field, and how that orthodoxy shifts in ways both subtle and profound. It is a personal tale of how economics works, as a human experience; the personal discoveries, false starts, and hopes nurtured and betrayed. The author ends with a summary of where the current debate in economics stands, and offers a new line of approach to the modelling of business cycles.