Janacek's Glagolitic Mass, a cantata for soloists, choir, orchestra and organ, was written in 1926 to a tex in the Old Church Slavonic language; from an early age Janacek had been passionate about the traditions of the Slavic peoples. Stephen Johnson explores this mighty work, playing illustrative excerpts and the whole work from a recording of the mass by the Czech Philharmonic Orchestra conducted by Karel Ancerl.