Brahms dedicated his German Requiem to his late mentor Schumann, his late mother, and the whole of humanity. Departing from the traditional Latin Catholic mass, he selected texts from Luther's translation of the Bible, producing a nonliturgical requiem: instead of a prayer for souls facing the Last Judgment, this is a meditation on death meant to console the living. The chorus is the current that flows through the seven movements, suspended ethereally above the orchestra or cutting through it majestically. Under conductor Kent Nagano the CSO will perform Wolfgang Rihm's four orchestral pieces Das Lesen der Schrift as interludes between movements. I have reservations about this augmentation, premiered by Nagano in 2002, but I have none at all about the forces he marshals here: the shining Swedish soprano Miah Persson, rich German baritone Christian Gerhaher, and the superb CSO chorus. The concert opens with works by Bernd Alois Zimmermann and Heinrich Schutz; a preconcert lecture begins at 7 PM. The program repeats at 8 PM Saturday, May 5, and 7:30 PM Tuesday, May 8. a 8 PM, Orchestra Hall, Symphony Center, 220 S. Michigan, 312-294-3000 or 800-223-7114, $24-$199.