On March 25, 1436, Dufay's motet Nuper rosarum flores was performed at the consecration of Cathedral of Santa Maria del Fiore in Florence. This is the most common account of this work in the history of European music, yet it is but an over simplified statement. The fact is that any piece of composition involves ideas and historical background in which it is created. This article tries to contextualize Nuper rosarum flores by reconsidering the cultural, historical, social background of the first half of the 15th century in order to appreciate and understand the work properly.