Marx views his own social thought as involving some definite ideas about the nature of ultimate reality, the source of human know ledge and other matters which philosophers would place under the rubric of ‘metaphysics and epistemology’. He does so because he regards his thought as a vehicle of the proletarian movement, and believes that a distinctively ‘materialist’ world outlook harmonizes with the historical practice of the proletariat and with the produc tive powers of modern scientific technology which make proletar ian emancipation possible. There are indications of what Marx understood by his ‘materialism’ scattered through his writings, but chiefly in his earlier writings (produced between 1844 and 1846). Marx never wrote at length on the theme, however, or gave his own materialism any systematic focus. In the Theses on Feuerbach, Marx is at pains to distinguish his materialism from that of previous materialists, but he tells us very little about what ‘materialism’ itself is supposed to be.