The circumstances under which this paper was read are narrated at the beginning of the work. The paper was never published during the lifetime of Marx. It was found amongst his papers after the death of Engels. Among many other characteristics of Marx, this paper shows two especially. These are his patient willingness to make the meaning of his ideas plain to the humblest student, and the extraordinary clearness of those ideas. In a partial sense the present volume is an epitome of the first volume of Capital. More than one of us have attempted to analyze and simplify that volume, with not too much success perhaps. In fact, a witty friend and commentator has suggested that what is now required is an explanation by Marx of our explanations of him. I am often asked what is the best succession of books for the student to acquire the fundamental principles of Socialism. The question is a difficult one to answer. But, by way of suggestion, one might say, first, Engels' Socialism, Scientific And Utopian, then the present work, the first volume of Capital, and the Student's Marx. My small part in the preparation of this work has been reading the manuscript, making a few suggestions as to English forms of expression, dividing the work up into chapters and naming the chapters, and revising the proofs for press. All the rest, and by far the most important part, of the work has been done by her whose name appears on the title page. The present volume has already been translated into German.