The theories and methods of such men as Adam Smith, Thomas Malthus, David Ricardo, J.S.Mill, Marx, Alfred Marshall and Keynes are often relevant to us today. In his analysis, the author assesses the thought of a number of important economists both in terms of the issues of their day and in relation to modern economic thought. By concentrating on the greatest exponents he highlights the central properties of the four main schools of economic thought - classical, Marxian, neo-classical and Keynesian - and shows that, although each of these traditions is rooted in a different stage of economic development, they can all provide insights into the recurring problems of modern economics.