Piketty defines capital as any asset that generates a monetary return. It encompasses physical capital, such as real estate and factories; intangible capital, such as brands and patents; and financial assets, such as stocks and bonds. In modern economics, the term “capital” has been purged of its ideological fire and is treated as just another “factor of production,” which, like labor and land, earns a competitive rate of return based upon its productivity. A popular model of economic growth developed by Robert Solow, one of Piketty’s former colleagues at M.I.T., purports to show how the economy progresses along a “balanced growth path,” with the shares of national income received by the owners of capital and labor remaining constant over time. This doesn’t jibe with modern reality. In the United States, for example, the share of income going to wages and other forms of labor compensation dropped from sixty-eight per cent in 1970 to sixty-two per cent in 2010—a decline of close to a trillion dollars.