This study reviews some of the arguments offered about economics as a science, presents the concepts of political economy, and discusses the principles of the macro economy as put forth by John Maynard Keynes in "The General Theory." It also covers the idea of the public economy advanced by the classical economists and augmented by the work of Paul Samuelson, Richard Musgrave, Gordon Tullock and James Buchanan. It examines the role of the economist as a teacher, a political economist, and as an adviser to policy makers.