… is from page 135 of the 2016 second edition of Thomas Sowell’s Wealth, Poverty and Politics :
Economic and social progress, whether among individuals, groups or nations, depends on both tangible and intangible factors. The tangible factors would include geography and existing physical wealth as a foundation for economic growth. The key intangible is human capital, and among the varieties of human capital is what has been aptly called “the radius of trust” within which individuals and groups cooperate in economic and social endeavors. Attitudes toward work and attitudes toward progress itself are also among the intangibles. What is tangible may make a stronger visible impression but it is by no means certain that its economic effect is greater than the economic effect of intangibles included in the concept of culture.