The German Ideology, co-written with Engels in 1845, was also unpublished but this is where we see Marx beginning to develop his theory of history. The Communist Manifestois perhaps Marx's most widely read work, even if it is not the best guide to his thought. This was again jointly written with Engels and published with a great sense of excitement as Marx returned to Germany from exile to take part in the revolution of 1848. With the failure of the revolution Marx moved to London where he remained for the rest of his life. He now concentratedon the study of economics, producing, in 1859, his Contribution to a Critique of Political Economy. This is largely remembered for its Preface, in which Marx sketches out what he calls 'the guiding principles' of his thought, on which many interpretations of historical materialism are based. Marx's main economic work is of course, Capital Volume 1, published in 1867, althogh Volume 3, edited by Engels, and published posthumously in 1894, contains much of interest. Finally, the late pamphlet Critique of the Gotha Programme (1875) is an important source for Marx's reflections on the nature and organisation of communist society.