There have always been markets. Capitalism, by contrast, is relatively new. Its laws of motion first emerged in Europe in the fifteenth and sixteenth centuries, and reached escape velocity with industrialization in the eighteenth and nineteenth.

If capitalism didn’t invent markets, however, it did make markets much more important. The historian Robert Brenner observes that capitalism is defined above all by market dependence. Pre-capitalist peasants can trade and barter, but they don’t depend on the market for life’s necessities: they grow their own food. In capitalist societies, on the other hand, the market mediates your access to the means of subsistence. You must buy what you need to survive, and to have the money to do so, you must sell your labor power for a wage.

Market dependence doesn’t exist for its own sake. It serves an important function: to facilitate accumulation. Accumulation is the aim of any capitalist arrangement: to take a sum of value and make more value out of it. While markets are certainly central to capitalism, they aren’t what makes it tick. Accumulation is. To put it in a more Marxist idiom, capital is value in motion. As it moves, it expands. Capitalism, then, is a way to organize human societies for the purpose of making capital move.

There are a few different methods for making capital move. The principal one is for capitalists to purchase people’s labor power, use it to create new value in the form of commodities, and then realize that value as profit by selling those commodities. A portion of the proceeds are reinvested into expanding production, so even more commodities can be made at lower cost, thus enabling our capitalist to compete effectively with the other capitalists selling the same commodities.

This may seem entirely obvious, but it’s actually a very distinctive way of doing things. In other modes of social organization, the point of production is to directly fulfill people’s needs: think of subsistence farmers, growing food for their families to eat. Or the point is to make the rulers rich: think of the slaves of ancient Rome, doing the dirty work so that imperial elites could lead lives of luxury.

What makes capitalism so unusual is that production (and accumulation) isn’t for anything exactly, aside from making it possible to produce (and accumulate) more. This obsession gives capitalism its extraordinary dynamism, and its revolutionary force. It utterly transforms how humans live and, above all, how they produce. Capitalism forces people to produce together, in increasingly complex combinations of labor. Production is no longer solitary, but social.