THE PRESENT VOLUME represents the extension of Keynes' General Theory by a group of well-known economists. The es- says in this volume are entirely new materials, each taking Keynes' work as a frame of reference for searching criticisms, further explorations, imaginative extrapolations, and novel insights, yet all trying to add something to a superstructure on the foundation of the General Theory. Here is to be found the unity and import of the volume as a whole, despite the diversity of the topics discussed and the variety of the styles pursued. So that a maximum of coherence might be achieved, the contributors were asked to focus their essays on specific but related aspects of Keynes. In addition, part of the whole effort has been to ap- praise economic ideas on their own merits, whether or not those ideas are associated with the name of Keynes.