Marx noted that labor power becoming a commodity allowed the capitalist to pay the exchange value of labor power, but at a lower value than that which it produced. Proletariats had the option of selling their labor to capitalists in exchange for wages that were supposed to provide workers with the full value of their labor. However, their labor was undervalued by capitalists in order to create surplus value. Surplus value was the profit created by labor that was not paid to the worker. The capitalists were then able to reinvest in production in the hope of increasing their profit and power. This would have been an alienation of workers from their work because the capitalist market did not allow workers to be paid the value of their work, with employers' incentives driven by competition to create the most profit. Marx believed that workers were not protected from exploitation and that the extraction of surplus value from human labor was the root of class.