The article revisits some aspects of the historical debate concerning the determination of the «just price» in early modern economic theory and examines critical points in its development. Both medieval and early modern moral thought recognized the necessity of not letting economic partners establish values and prices of their transactions on their own. Some theologians argued that this task belonged to the acting political powers; others preferred a public market place ruled by laws in order avoid the formation of monopolies and to regulate competition. The article has two foci. First, it highlights the contextual significance of these contemporary theoretical differences. Second, it argues the need to rethink some of the «traditional historical interpretations» that emphasize the link between the scholastic's economic theory and the neoclassical market - and in particular its conception of the communis aestimatio.