The meaning of the term “national income” has actually never been fixed, fluctuating with the latest intellectual currents and the imperatives of the moment. Every era has its own idiosyncratic ideas about what defines a country’s wealth. Take Adam Smith, father of modern economics, who believed that the wealth of nations was founded not only on agriculture, but also on manufacturing. The entire service economy, by contrast–a sector that spans everything from entertainers to lawyers and constitutes roughly two-thirds of the modern economy–Smith argued “adds to the value of nothing.”18
