In the context of the War of the Spanish Succession, the duty of any composer was to celebrate not only the greatness of a deity in religious pieces, but also the power of their sponsors. Jordi Savall invites us to relive the creation of two dazzling masterpieces of polychoral music : the Missa Scala Aretina by Francesc Valls (one of the last pieces to make overt reference to Guido of Arezzo’s famous hexachord) and the Mass for 2 Choruses and Orchestras by Henry Desmarest.