To illustrate this, Rosenstein-Rodan gives the example of a shoe industry. If a country makes large investments in the shoe industry, all the disguisedly employed labor from the other industries find work and a source of income, leading to a rise in production of shoes and their own incomes. This increased income will not be expended only on buying shoes. It is conceivable that the increased incomes will lead to increased spending on other products too. However, there is no corresponding supply of these products to satisfy this increased demand for the other goods. Following the basic market forces of demand and supply, the prices of these commodities will rise. To avoid such a situation, investment must be spread out amongst different industries.