Keynes' General Theory is one of the books that have made a universal impact; but it could scarcely have gained such a reputation had it not been deeply marked by the experience of the age in which it was written. In the very different world of today, a fresh appraisal is necessary in order that the ephemeral and the permanent (between which Keynes could naturally hardly be expected to distinguish) may be separated with the inestimable assistance of hindsight. Sir John Hicks was himself responsible for a widely employed approach to the thought of Keynes, but he has come to feel that a new presentation is now needed. This distinguished study, which is a contribution to the work of reappraisal, is the result.