Smith upheld the labor theory of value in its early form, according to which the value of a good is determined by the amount of labor required for its production. However, he later emphasized the market price, which is influenced by supply and demand. Marx, on the other hand, adopted the labor theory of value and further developed it: for him, the value of a commodity lies in the socially necessary labor time required for its production. Marx saw this as the foundation of exploitation under capitalism, since workers create more value than they receive in the form of wages.