“El preu real de cada cosa, el que cada cosa costa realment a l'home que vol adquirir-la, és el treball i la molèstia d'adquirir-la.”
Text de l'edició incorporada · anglès
“The real price of every thing, what every thing really costs to the man who wants to acquire it, is the toil and trouble of acquiring it.”
— Adam Smith, An Inquiry into the Nature and Causes of the Wealth of Nations