Preface THE collection and publication of these essays in book form is not intended to give them a greater importance as a whole than would be due to each individually. For the most part they are attempts, arising out of actual work for the party, to clarify the theoretical problems of the revolutionary movement in the mind of the author and his readers. The exceptions to this are the two essays Reification and the Consciousness of the Proletariat and Towards a Methodology of the Problem of Organisation which were both written specially for this collection during a period of enforced leisure. They, too, are based on already existing occasional pieces. Although they have now beenpartly revised, no systematic attempt as been made to remove the traces of the particular circum- stances in which they were written. In some cases a radical re of truth. Thus in the essay on The Changing Function of Historical Materialism we can still hear the echoes of those exaggeratedly sanguine hopes that many of us cherished concern ing the duration and tempo of the revolution. The reader should not therefore, look to these essays for a complete scientific system Despite this the book does have a definite unity. This will be found in the sequence of the essays, which for this reason are best read in the order proposed. However, it would perhaps be advisable for readers unversed in philosophy to put off the chapter reification to the A few words of explanation-superfluous for many readers prominence given in the se pages to the presentation, interpretation and discussion of the theories of a Luxemburg. On this point I would say, firstly, that Rosa Luxemburg, alone among Marx,'s disciples, has made a real advance on his life's work in both the content and method of hi economic doctrines. She alone has found a ply them concretely to the present state of social development. Of course, in these pages, in pursuance of the task we have set ourselves, it is the methodological aspect of these questions that will be most