Jordan, pp. 29-30, wrote:Marx

Marx rightly argued that naturalism thus understood ‘distinguishes itself both from idealism and materialism, constituting at the same time the unifying truth of both’. Although what men see, touch, or grasp are responses to external stimuli, the external objects are determined by the selective activity of the senses and the senses in turn are constantly modified by the biological, social, and cultural evolution of the human species. In a certain, sense, then, there are no natural data, no God-given external facts of nature, but only socially mediated objects.[45]The world as known to man is a man-made world; it is the totality of ‘things for us’ and not of ‘things-in-themselves’. The only knowable is the world that appears in man’s experience, that is causally transformed by human action, divided into species and particulars, class members and classes, articulated into objects and their relations, into things with a definite form, arrangement, and structure, and cut out from the chaotic mass of the pre-existing world as it persists by itself. This humanized world is knowable because it is a world determined by man, the outcome, as Marx said in the first Thesis on Feuerbach, of ‘human sensuous activity’. As a natural being man shapes the environment according to his needs, and the needs determine the articulation of the world into separate things and their connections. External objects are, as it were, the objectified centres of resistance in the environment encountered by the human drives striving for the satisfaction of needs. If the needs were different, the world would look differently too, as it does to other animal species.