Written before the collapse of the socialist system in Eastern Europe, this book offers an analysis of the Marxian labour theory of value, Marx's main scientific legacy. After reconstructing the "prototype" of this theory - which is the theory as it was left by Marx himself in "Capital" - the author proceeds to a careful and detailed analysis of its foundational problems, taking into account Boehm-Bawerk's important criticisms. After introducing advanced contemporary formal tool the author proceeds to a discussion of the dialectical method, just in order to tackle the foundational problems of the theory. He provides a definition of abstract labour and then proceeds to prove the existence of a measurement of abstract labour - for instance the existence of numerical labour-values. Using this result, the author provides axiomatic foundations for the theory of value and then proves the existance of a Marxian competitive equilibrium, which is tantamount to the proof of the possibility of reproduction for a capitalist economy. The author finishes the book by showing how the problems of the prototype are solved, by reconstructing the Leonitief model of the labour theory of value on the new logical basis. This book should be of interest to philosophers of science and economics and those interested in the scientific legacy of Karl Marx.