Every week I have to turn down offers to attend concerts and productions, but this one is hurtin'. Musica Sacra is celebrating its 50th birthday at Jordan Hall this weekend, as well as the 30th year that it has been led by the nifty and talented Mary Beekman, at left . Boston Cecilia and soloists Emily Hindrichs, soprano, and Dana Whiteside, baritone, will join them for the party. The concert's centerpiece will be the Brahms German Requiem, which I know sounds funereal but which is a wonderful and deeply touching piece. More info and tickets available here.