“It does not distract from the economic fundamentals set forth by Adam Smith to point out that the wealth of nations would come to be predominantly the acquired abilities of people — their education, experience, skills, and health. No one at Adam Smith’s time could have foreseen that there would be a nation in which four-fifths of the national income would be derived from earnings and only a fifth of it from property. Yet the United States is such a nation. We have learned that advances in knowledge are an important source of wealth and income. We appear, however, to know less about the functions of organization than Adam Smith knew.”
Theodore W. Schultz, Investing in People: The Economics of Population Quality (1981), p. 140