All ideas, Marx would argue, are a product of their time and place in history. Marx formed his ideas as Europe embarked upon the massive transformations which changed traditional, peasant farming societies into modern, industrial ones.

As he wrote, for the first time large industrial cities were being developed. Filth, overcrowding, sickness and poverty existed alongside a new urban rich.

Marx was not alone in offering an analysis of these changing conditions. What is distinctive about his thought is that he sees the key factor in understanding the development of these new societies, the thing which at the end of the day shapes how the society is organised, what we think and believe, who we are and what we can become, is not the new industrial technologies nor even the new urban spaces but the way in which production is organised.

The new world that Marx was analysing was the first flowering of a mature capitalist system. Today we are so used to talk of ‘market forces’ that it is hard to remember that there is nothing natural or God-given about the capitalist economic system. It exists because human beings have created it and sustained it. The key difference between capitalism and the economic systems that had gone before it is the way in which the relationships between property and labour are organised.

Capital lies in private hands and those who own it seek profit as their reward for its deployment in the economy. Investment - whether in farming, mining, manufacturing or services - requires workers if it is to see a return; there is no point building a factory unless there are workers to labour in it. As well as bringing into being a new class of owner, capitalism also requires a new kind of worker: one tied not by traditional loyalties or by relationships of servitude, but formally free labour entering into a contractual relationship with the employers for wages.

When Marx looked at this relationship between the owners of capital and those who have to sell their labour power to survive, he saw not a fair deal, but a system of exploitation.