 In De contractibus Olivi discusses several topics related to the morality of economic activity, such as contracts, commerce, usury, value, and capital. The first question of the treatise serves as an illustrative example of his general approach to economics. It focuses on the notion of just price, which Olivi analyzes with the intention of setting normative limits that regulate but do not completely prevent economic activity. As in Quid ponat ius, he proposes a theory that reconciles two sets of opposing arguments. According to the first set of arguments, a voluntary contract between a buyer and a seller suffices to establish a just price. The price the parties freely agree upon is just, because any other way of setting the just price would make commercial activities liable to immorality. Without full knowledge of the just price, the buyer and the seller might accidentally deviate from it and thus sin. By contrast, the second set of arguments aims to prove that there must be objectively determinable limits for the just price. Otherwise there might be a situation in which someone charges an extremely high price for a glass of water, and one who is dying of thirst pays it voluntarily, thereby making the price just. Thus, all deviations from the objectively just price are against the principles of justice.