 In the writings of St. Thomas Aquinas, we find the beginnings of a much more sophisticated and promising approach to questions such as this. In his Summa Theologiae, Aquinas sought to answer the question of “whether a man may lawfully sell a thing for more than it is worth?” The “worth” of a thing, for Aquinas, was its just price. And the just price, according to Aquinas, appears to have been simply the prevailing market price (Summa Theologiae, part 2, second part, question 77; see also de Roover 1958 and Friedman 1980). Rather than relying on some fixed notion of proportionality, Aquinas’ just price will be responsive to considerations of supply and demand. But not just any price that two individuals mutually agree upon will be deemed just on Aquinas’ standard. Thus, a seller who takes advantage of fraud, or a temporary monopoly, to charge an excessive price for an item would be acting unjustly, insofar as his price is in excess of the price at which similar goods typically sell in the relevant market. But Aquinas saw nothing inherently sinful in selling a good for more than one paid for it, or with charging enough to earn a profit, or to compensate for risks involved in the productive process. Seeking profit for its own sake may involve a certain sort of “debasement”, but profit can also be sought in order to fulfill necessary or even virtuous ends.