The German Ideology
As Martin Nicolaus and others have argued, the "Grundrisse" is crucial for understanding Marx's mature analysis of capitalism, even though, historically, it has been far less influential in the development of the various strands of Marxist theory than earlier texts such as the "Communist Manifesto", the "Economic and Philosophic Manuscripts of 1844", and "The German Ideology". Towards the end of his life, Marx, according to Nicolaus, viewed the latter “with a scepticism bordering on rejection.” The "Grundrisse", on the other hand, was one of the few texts which Marx spoke of “with a tone of achievement and a sense of accomplishment.” If this is true, possibly the main reason is that the more substantive first part of "The German Ideology" was largely written by Friedrich Engels while the subsequent parts, satirizing the linguistic apostasies and word-mongering of Left-Hegelian philosophers, were written by Marx himself.