(Lat. gradus = level) a liturgical book that contains the chants for the mass that are chanted by the Schola and not by the priest. This contains both the chants that change depending on the day or the occasion (proprium, e.g. the hallelujah call) as well as the chants that always remain the same (ordinarium, e.g. the sanctus). Late medieval gradual manuscripts can be very large because entire groups of singers performed using one manuscript. The name is derived from the steps of the ambo where the schola stood.