Who was Hildegarde von Bingen? And why is she revered by musicologists and the Vatican? Rarely are the visions of one who lived during the 12th century taken to heart, but the writings of this nun and adviser to popes and emperors have so enraptured her followers that the pope recently announced he will elevate her to sainthood next year.

Anonymous 4, the vocal ensemble with a repertoire spanning more than a thousand years, brings Hildegarde to life in a concert of works selected from her extensive repertoire. Presented by the Folger Shakespeare Library, it takes place in Washington National Cathedral.