Nuper Rosarum Flores

   Renowned four-voiced motet of Guillaume Du Fay, composed for the reconsecration of Santa Maria del Fiore (Duomo) in Florence on 25 March 1436, with Pope Eugene IV in attendance. The motet treats its borrowed chant melody, the Introit {}Terribilis est locus iste, in expanded isorhythm. Each talea of the motet begins with a free duet in the upper voices, followed by the full four-voiced texture that includes two tenor voices singing the Introit a perfect fifth apart in a free canon. The entire motet includes four presentations of the cantus firmus (plus a concluding "Amen") in durational proportions of 6:4:2:3, unusual in that they do not become progressively faster as was customary in isorhythmic motets. Explanations include a correspondence to the architectural proportions of Filippo Brunelleschi’s famous dome and a reference to a biblical tradition about the ratio of the Temple of Solomon.