Reddit reviews The operas of Mozart

My favorite is A Song of Love and Death: The Meaning of Opera by Peter Conrad.

Excerpt:

>The characters of opera obey neither moral nor social law. They are women like Isolde with her erotic medicine chest or Carmen with her intoxicating flower, men like the overworked phallic symbol Don Giovanni or Gounod's Faust who, rather than bothering with good works for mankind (to which the hero of Goethe's play commits himself), licks his lips and asks the devil to provide him with pleasures and young mistresses. Music buoys and bears along these clamorous creatures. What rises in and overflows from the orchestra pit is the geyser of their desires: they give voice to the promptings of the underground consciousness.

For books on individual composers:

Mozart's Operas by William Mann

Wagner's Ring and Its Symbols by Robert Donington