 Philosophers also draw a distinction between merit "de condigno" (Christ's merit), which is based on justice, and merit "proprie de congruo" (Mary's merit), founded on the friendship of charity.The concept was especially common in the late Middle Ages, when it was promoted heavily among the Franciscans, and often resisted by the Dominicans.It is an idea which was the subject of considerable theological debate, reaching a peak in the 15th century.