…if the citizens themselves devote their life to matters of trade, the way will be opened to many vices. Since the foremost tendency of tradesmen is to make money, greed is awakened in the hearts of the citizens through the pursuit of trade. The result is that everything in the city will become venal; good faith will be destroyed and the way opened to all kinds of trickery; each one will work only for his own profit, despising the public good; the cultivation of virtue will fail since honour, virtue’s reward, will be bestowed upon the rich. Thus, in such a city, civic life will necessarily be corrupted.
~ St. Thomas Aquinas, De Regno, 139