Originally published in 1871, The Theory of Political Economy was the first text to introduce the concept of utility theory into economics and the use of calculus as a way to simplify and present economic problems. In this classic work Jevons re-formulated the central problem of economics as one of how to maximise overall utility with a set amount of means of production. Utility expressed as a function became the basis of the a new theory of value which substantially differs from the classical political economists' labour theory of value. Drawing on his roots in the natural sciences Jevons revolutionised the tools and methods associated with political economy and kick-started the metamorphosis of the discipline. A century after its original publication The Theory of Political Economy continues to exert its influence in the teaching and study of modern economics. This re-issued classic contains a new introduction by Dr Harro Maas who explores the rich contextual history of Jevons and the Theory and the continued influence it has on modern day economics.