"The propensity to truck, barter and exchange one thing for another is common to all men, and to be found in no other race of animals"

Adam Smith's quote is a recommendation to the concept of economic exchange, which is a fundamental part of human society. He is suggesting that the ability to trade and exchange products and services is a distinct quality of humans, and is not discovered in any other types. This is an important principle in economics, as it enables the effective allotment of resources and the development of wealth. Smith's quote also implies that humans have a natural desire to engage in financial exchange, which is why it is so widespread in our society. This quote highlights the value of economic exchange in human society, and how it has actually been a driving force behind our development and advancement.