The formula M-C-M represents how capitalists gain and increase their wealth. It begins with money (M) which is used to purchase (C) commodities, like raw materials and labor. After producing said commodities, they are then sold in turn for more money (M’). The surplus value (profit) is what distinguishes (M) from (M’). Surplus value is the extra work that workers produce, which stems beyond the wages they earn and capitalist turn a profit from. Those profits are then reinvested by the capitalist to develop more production and increase their wealth. This process of making profits and pour back it into the business is what helps keep the cycle of wealth exponentially growing in capitalist economy.