The science of Political Economy rests upon a few notions of an apparently simple character. Utility, wealth, value, commodity, labour, land, capital, are the elements of the subject; and whoever has a thorough comprehension of their nature must possess or be soon able to acquire a knowledge of the whole science. As almost every economic writer has remarked, it is in treating the simple elements that we require the most care and precision, since the least error of conception must vitiate all our deductions. William Stanley Jevons is regarded by many as bringing mathematical methods to the study of economics. The Theory of Political Economy brought together maths and the theory of utility, this contribution marked Jevons as a leading political economist of his time. "Jevons's The Theory of Political Economy marks the watershed between classical and neoclassical economics. Jevons provided lengthy arguments for the mathematization of economic theory as well as for the priority of the utility theory of value in place of the labour theory of value that had been central to economics since John Locke. This book will enlighten any reader wishing to understand the essential nature of contemporary mainstream economics. And like all pathbreaking works, it also raises questions that have since been forgotten, questions about the measurement of utility, the justification for using continuous mathematical functions, or the definition of capital. Spending time with Jevon's brilliant and polymathic mind will amply reward any inquisitive reader."