These three essays by the independent German Marxist Karl Korsch offer expositions, often in polemical form, of basic Marxist ideas. Since they cover both sociology and economics, they are excellent guides for the student on the most introductory, though not the most elementary, level. The first essay, “Leading Principles of Marxism,” takes up Marxism on the plane of sociology and deals with the relation of Marxism to Comte and positivism, and to bourgeois sociology in general. The second, his introduction to the 1932 German edition of Capital, consists of an assessment of the work in human thought and an important reader’s guide to Volume I. The third, “Why I Am a Marxist,” is a polemic against various distortions in Marxism and an affirmation of the revolutionary, as against the academic, character of Marxism.