In his ensemble work Bereshit, completed in 2012, Matthias Pintscher musically reflects on the act of creation, continuing his exploration of Old Testament themes— the work’s title is the first word of the Hebrew Torah. “It’s a beginning of the beginning, out of absolute darkness and shapelessness,” the composer-conductor says. He also leads the Boulez Ensemble in Harrison Birtwistle’s Secret Theatre, written in 1984 and inspired by the eponymous poem by Robert Graves. For Bach’s “Wedding Cantata,” the ensemble is joined by soprano Keren Motseri.