For the past few years the Cantata Singers have organized their seasons around a single composer, for example Kurt Weill and Benjamin Britten. This focus and the deep musical knowledge of David Hoose and his colleagues have resulted in marvels of “curated” programming, as some have called it. This season the principal composer, Heinrich Schütz, points the way to the Cantata Singers’ original focus, Johann Sebastian Bach and lays out in rich array of Schütz’s context and legacy throughout western music, from his great contemporary, Claudio Monteverdi, to Boston’s own John Harbison. As in previous years, the programs for all four concerts are contained in one elegant book, which amounts to a convenient introduction to the principle composer, his cultural milieu, and his influence. The premise is basically forward-looking, and the programs are planned to bring out threads which lead up to our present musical environment: hence it is entirely appropriate that historical performance practice is not on the Cantata Singers’ agenda. Chorus and soloists sing with vibrato, and not a single gut string or original instrument is in evidence.