Marx’s basic position was famously summarised in The German Ideology:
The production of ideas, concepts and consciousness is first of all directly interwoven with the material intercourse of man, the language of real life. Conceiving, thinking, the spiritual intercourse of men, appear here as the direct efflux of men’s material behaviour... we do not proceed from what men say, imagine, conceive, nor from men as described, thought of, imagined, conceived, in order to arrive at corporeal man; rather we proceed from the really active man... Consciousness does not determine life: life determines consciousness.
It was the German philosopher Hegel who gave the conception of consciousness a social-historical perspective — Marx, who learned a great deal from him, took it further by putting it on a materialist instead of an idealist footing.
Art, like any other subject, cannot be understood by isolating one aspect then elevating it into a system. It must be seen as a totality — a sum of processes. Art is the product of history, of local culture, of artists’ personal experiences, of the available materials, of what earlier artworks are available as models, of the artist’s mood on the day, of the expectations of people in authority, and many other influences. But all of these aspects have to be considered in their concrete, historical context.
This is actually very obvious. It was not possible to create bronze statues until the development of metallurgy enabled us to extract tin and copper ores and combine them into an alloy. In the same way, no artist could explore themes from Christian mythology until the Christian religion emerged, thousands of years after humanity had, in blissful ignorance of Jesus, already built sophisticated societies and produced masterpieces of art.
Marx and Engels therefore insist upon seeing things historically:
Does it require deep intuition to comprehend that man’s ideas, views and conceptions, in one word, man’s consciousness, change with every change in the conditions of his material existence, in his social relations and his social life?
What else does the history of ideas prove, than that intellectual production changes its character in proportion as material production is changed?
Therefore we must explore, as a necessary complement to aesthetic questions, Marxist theory on society and history. The French philosopher Descartes famously said that “I think, therefore I am.”  In fact his maxim was the wrong way round. Mind and body develop as a unity, but it is impossible for anybody to think without the neurological equipment provided by matter, whereas matter may certainly exist without thought, as the nearest chair or pebble will prove in a moment. “Thinking and being are thus certainly distinct, but at the same time they are in unity with each other” (Marx) .
Being determines consciousness
In Marxist philosophy, human beings exist in a subject-object relationship with a material world of which they are themselves also a part. In The German Ideology, Marx and Engels set out the materialist approach to the relationship between ideas and reality:
The first premise of all human history is, of course, the existence of living human individuals. Thus the first fact to be established is the physical organisation of these individuals and their consequent relation to the rest of nature... The writing of history must always set out from these natural bases and their modification in the course of history through the action of men...
By producing their means of subsistence men are indirectly producing their actual material life.
The way in which men produce their means of subsistence depends first of all on the nature of the actual means of subsistence they find in existence and have to reproduce. This mode of production must not be considered simply as being the production of the physical existence of the individuals. Rather it is a definite form of activity of these individuals, a definite form of expressing their life, a definite mode of life on their part. As individuals express their life, so they are. What they are, therefore, coincides with their production, both with what they produce and with how they produce. The nature of individuals thus depends on the material conditions determining their production.
This approach was radical at a time when philosophers were pre-occupied with variations of idealism: that is, they assumed that history was a history of ideas through which humans transformed their social conditions. In fact we must draw our conclusions from actual concrete conditions. All our ideas develop from the material facts of our lives — the mode of production, the class structure, the conflicting ideologies between and within classes, and so on  — and these heavily influence both our day-to-day experience and the climate of our intellectual assumptions.
The material context conditions our way of thinking whether we realise it or not; even when we know it is happening, we can never completely overcome it because we are limited by history. Just as no artist could depict a television in their work until the possibility of televisions had been conceived, we cannot think ideas until society has reached a point that makes it possible for us to create those ideas.
Capitalism — contrary to bourgeois theorists who want to suggest it is an eternal aspect of human nature — did not exist in the world until a layer of people began to employ wage labour in 14th-century Europe. Likewise, nobody was writing Marxist treatises in the Classic Maya civilisation of 250–900 CE, not because of some random chance but because the material conditions that made the ideology of Marxism possible — industrialisation and the development of the proletariat — simply had not yet appeared.
The art of the Renaissance grew from the revolutionary rise of capitalism within feudal society; its emphasis upon perspective, identification with classical art and return to naturalism developed from the humanism and individualism of the early bourgeoisie. Broadly, the bourgeois worldview shifted art from representing the world in spiritual terms to representing it in human and material terms. A painting like Hans Holbein’s The Ambassadors could never have been created during the Medieval period. In order to understand why it could not, we need to understand the development of productive forces. Otherwise we are simply left with a series of ‘styles’ that seem to pop up at the whim of artists.
‘The Ambassadors’ by Holbein. The sensuous realism of this work represents a radical shift away from Medieval art. Larger image here.
Recognising the influence of particular conditions in this way does not demote or belittle art . No art can be reduced to its social conditioning; at the same time, no art is demeaned by pointing out that social conditioning exists. No theory of art will be of value that does not ground itself in the relationships with which art, inescapably, engages with the world.
Marxists are probably more aware than anybody that their own theoretical framework is itself a part of history and will change and grow over time. All classes are transitory. But the proletariat is uniquely at ease with its historical nature. Marxism aims for a society in which there will no longer be a proletariat because there will be no classes — the proletariat is the only class in history whose ultimate goal is its own dissolution.
Our susceptibility to material conditions does not make us automatons without any freedom of action.
Materialist epistemology argues that consciousness proceeds from matter, and that cognition is the ‘reflection’ of external reality in consciousness. Marx wrote:
To Hegel, the process of thinking, which, under the name of ‘the Idea’, he even transforms into an independent subject, is the demiurgos (the creator, the maker) of the real world... With me, on the contrary, the ideal is nothing else than the material world reflected by the human mind, and translated into forms of thought.
This point of view was confirmed by Engels in Anti-Dühring:
If the... question is raised: what thought and consciousness really are, and where they come from; it becomes apparent that they are products of the human brain and that man himself is a product of Nature, which has developed in and along with its environment; hence it is self-evident that the products of the human brain, being in the last analysis also products of Nature, do not contradict the rest of Nature’s interconnections but are in correspondence with them...
Hegel was an idealist, that is to say, the thoughts within his mind were to him not the more or less abstract images of real things and processes, but on the contrary, things and their development were to him only the images, made real, of the ‘Idea’ existing somewhere or other before the world existed.
This theory of ‘reflection’ was later also expanded upon by Lenin.
However, Marxists see the world as dialectical. Consciousness does not passively ‘reflect’ being. If it did, there would be little need to consider consciousness at all except as an aspect of matter. For Marx, there was no separation of the two, as he made clear in his criticism of Feuerbach’s passive conception of the sensuous world:
He does not see how the sensuous world around him is, not a thing given direct from all eternity, remaining ever the same, but the product of industry and of the state of society; and, indeed, in the sense that it is an historical product, the result of the activity of a whole succession of generations, each standing on the shoulders of the preceding one, developing its industry and its intercourse, modifying its social system according to the changed needs.
The conception of human consciousness in the abstract, as a passive product of being, derives from pre-Marxist philosophy and is explicitly rejected by Marx. Dialectics insist upon change — they also insist that things and processes react upon each other. Just as being determines consciousness, consciousness can determine being: good examples are the French, Russian and other Revolutions, in which human action changed the fundamental basis of the economy. They became possible because of the advances in material forces, but could only happen through human action, which in turn depended upon ideological conviction.
So the insistence upon the primacy of being does not preclude or demote consciousness. It means that consciousness can only be understood as a relationship with the material world: consciousness retains some autonomy, but within a broader framework upon which it ultimately depends. In practice, we cannot separate being from consciousness in humans — they may only be separated in the abstract.
We shall clarify this ‘autonomy’ of consciousness further by looking at the Marxist theory of ideology. First, however, we need to consider the concept of base and superstructure.
 Marx and Engels, from Part I of The German Ideology (1845–6).
 Marx and Engels, ‘Proletarians and Communists’, Manifesto of the Communist Party (1848).
 In French, ‘Je pense donc je suis.’ René Descartes, Discourse on Method (1637).
 Marx, Third Manuscript, the 1844 Manuscripts (1844).
 Marx and Engels, from Part I of The German Ideology (1845–6).
 We shall discuss the idea of class society in more detail when we look at its first appearance in the early civilisations.
 For example, the art theorist Ellen Dissanayake, in her book Homo Aestheticus (1992), writes “To earlier generations, art was a divine and mysterious visitation. More recently it was demoted to... part of the ‘superstructure’, as materialist philosophy would have it” [my italics]. Dissanayake is concerned that if art is superstructural, it cannot be a necessary part of our biological make-up; I shall post an article on this topic.
 Afterward to the Second Edition of Capital, vol. 1 (1867).
 Engels, Part I, section III of Anti-Dühring (1877). The word Engels uses in the original German is Abbilder.
 Marx and Engels, Part I, section B of The German Ideology (1845–6).