Monteverdi’s Vespro della beata Vergine is a landmark work of the early Baroque, sitting at the crossroads of Renaissance polyphony and the novel use of basso continuo heard in his first opera, L’Orfeo. The “1610 Vespers” redefined what sacred music could sound like — emotionally immediate, virtuosic, both looking back to the past and driving forward into the future. Monteverdi …