There’s no better place to get close to Guillaume Dufay than within sight of Florence Cathedral. Walking through that church’s grand 14th-century interior – or, even better, looking up at its magnificent red-tiled cupola, built in the 15th century – the modern visitor gazes at structures that Dufay not only knew 500 years ago, but which also sparked his imagination. They say that architecture is frozen music, but in this case the metaphor can truly be reversed: for the building of Florence Cathedral gave rise to a piece of music that may fairly be called ‘molten architecture’.

Guillaume Dufay

And by probing deep into this composition – the motet Nuper rosarum flores – we also peer into the life and mind of the most celebrated musician of...