From the preface: "The materialist conception of history is not only important because it allows us to explain history better than has been done up to now, but also because it enables us to make history better than has been hitherto done. And the latter is more important than the former. From the progress of the practice our theoretical knowledge grows and in the progress of the practice our theoretical progress is proved. No world-conception has been in so high a degree a philosophy of deeds as the dialectical materialism. Not only upon research but upon deeds do we rely to show the superiority of our philosophy. " Karl Kautsky (1854-1938), compiler of Karl Marx's Theories of Surplus Value (1905-10), has been rightly considered the successor of Engels in the intellectual leadership of the Marxian School. Kautsky was the founder of Die Neue Zeit and a political leader of the German Social Democrats. He denounced both Germany's aggression in World War I as well as the conduct of Russian Bolshevism after the 1917 Revolution. This book was originally published in 1906.