Adam Smith rejected the mercantilist focus on production, arguing that consumption was paramount to production. He added that mercantilism was popular among merchants because it was what is now called rent seeking. John Maynard Keynes argued that encouraging production was just as important as encouraging consumption, and he favored the "new mercantilism". Keynes also noted that in the early modern period the focus on the bullion supplies was reasonable. In an era before paper money, an increase in bullion was one of the few ways to increase the money supply. Keynes said mercantilist policies generally improved both domestic and foreign investment—domestic because the policies lowered the domestic rate of interest, and investment by foreigners by tending to create a favorable balance of trade. Keynes and other economists of the 20th century also realized that the balance of payments is an important concern. Keynes also supported government intervention in the economy as necessity, as did mercantilism.