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 it produced. Proletarians had the option of selling their labor to the capitalist in exchange for a wage, which was believed to be calculated to provide workers with the full value of their labor. However, their work 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. Capitalists were then able to reinvest in production in the hope of increasing their profits and power. This would have been the alienation of workers from their work because the capitalist market did not allow workers to be paid the value of their work, due to employers' competition-driven motivations to create maximum 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