The Magic Flute
Mozart belonged to a group of Freemasons.  The Magic Flute is full of Masonic symbols.  For example: the number three is an important number in masonry and there are lot of things in the opera that happen in threes:  there are three long chords at the beginning of overture, and the three chords appear again in the scene in the temple.  Even the key is E flat major which has a key signature of three flats.  There are three ladies, three young boys and three trials.  The scenery used in the early productions make it look as if the story comes from Egypt or somewhere in the Orient.  Mozart and Schickaneder meant this to have a Masonic meaning. The trials are similar to the rituals in Masonic ceremonies.