Jean Sibelius was the composer of seven authorized symphonies that stand like granitic monoliths at the heart of 20th century music. Less well known, perhaps, is the abundant incidental music he composed for the theater. Join me for an historic 1932 recording of selections written for the play “Belshazzar’s Feast,” with Robert Kajanus conducting, and a more recent, digital premiere of the complete incidental music composed for “Everyman,” made under the baton of Osmo Vänskä. Enjoy this neglected-but-worthwhile music on “Sibelius, Incidentally,” this Sunday night at 10 EDT on WWFM – The Classical Network and wwfm.org.