Unfinished business

Mozart is full of loose ends and extremes. One-off miniatures, contextless and unparalleled, of singular profundity and perfection — the A-minor rondo and B-minor adagio for piano, the pieces for glass harmonica and mechanical organ, the Masonic Funeral Music; and four of his most ambitious-scaled monuments — two quasi-religious operas, Idomeneo taking seria into realms of extraordinary sublimity, Zauberflöte adding to these a further range of humanistic sentiment, comedy, pathos, slapstick; and two quasi-operatic religious works, both unfinished, the C-minor Mass and the D-minor Requiem, which equally take him into otherwise untried realms.