“Blessed are those who mourn, for they shall be comforted.” Johannes Brahms wasn’t the religious type, but when his mother died he created one of the most heartfelt of all Requiems. Intended to console the living, it’s a radiant showcase for Mirga Gražinytė-Tyla, the CBSO Chorus and two truly exceptional soloists – and a ray of light after the darkness of Mozart’s startlingly powerful Wind Serenade.