This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The crisis of economics is much deeper than the crisis of the economy. It is also one of the major causes of the present economic crisis. After the Lehman Brothers bankruptcy and the subsequent economic shock, many economists thought it necessary to return to Keynesian theory. Keynes has given us a precious idea, but we should remind ourselves of recent history and study dispassionately why an anti-Keynesian revolution took place in the 1970s. The Oxford Economic Research Groups first observation implies that Keyness basic idea on investment was not empirically confirmed. This required a fundamental reorganization of Keyness system. Neoclassical economists often criticize classical theory of value for lacking demand theory.