which had already been set to music by Campra.  Idomeneo, King of Crete, on his way home from the siege of Troy, is overtaken by a terrific storm.  In despair of his life, he vows that, should he reach the shore alive, he will sacrifice the first human being he meets to Neptune.  This proves to be his son Idamante, who has been reigning in his stead during his absence.  When he finds out who the victim is—­for at first he does not recognise him—­he tries to evade his vow by sending Idamante away to foreign lands.  Electra the daughter of Agamemnon, driven from her country after the murder of her mother, has taken refuge in Crete, and Idomeneo bids his son return with her to Argos, and ascend the throne of the Atreidae.  Idamante loves Ilia, the daughter of Priam, who has been sent to Crete some time before as a prisoner from Troy, and is loved by her in return.  Nevertheless he bows to his father’s will, and is preparing to embark with Electra, when a storm arises, and a frightful sea monster issues from the waves and proceeds to devastate the land.  The terror-stricken people demand that the victim shall be produced, and Idomeneo is compelled to confess that he has doomed his son to destruction.  All are overcome with horror, but the priests begin to prepare for the sacrifice.  Suddenly cries of joy are heard, and Idamante, who has slain the monster single-handed, is brought in by the priests and people.  He is ready to die, and his father is preparing to strike the fatal blow, when Ilia rushes in and entreats to be allowed to die in his place.  The lovers are still pleading anxiously with each other when a subterranean noise is heard, the statue of Neptune rocks, and a solemn voice pronounces the will of the gods in majestic accents.  Idomeneo is to renounce the throne, and Idamante is to marry Ilia and reign in his stead.  Every one except Electra is vastly relieved, and the opera ends with dances and rejoicings.

The music of ‘Idomeneo’ is cast for the most part in Italian form, though the influence of Gluck is obvious in many points, particularly in the scene of the oracle.  Here we find Mozart in his maturity for the first time; he has become a man, and put away childish things.  In two points ‘Idomeneo’ is superior to any opera that had previously been written—­in the concerted music (the choruses as well as the trios and quartets), and in the instrumentation.  The chorus is promoted from the part which it usually plays in Gluck, that of a passive spectator.  It joins in the drama, and takes an active part in the development of the plot, and the music which it is called upon to sing is often finer and more truly dramatic than that allotted to the solo singers.  But the chorus had already been used effectively by Gluck and other composers; it is in his solo concerted music that Mozart forges ahead of all possible rivals.  The power which he shows of contrasting the conflicting emotions of his characters in elaborate concerted movements