A main theme of the play is the gap between appearance and reality. This theme is represented in a physical sense by the opera house, a simple theater on the surface but a labyrinth of tunnels and exotic rooms underneath. The nature of stage presentations in itself is a fabrication of reality, and the Phantom is a master of illusion, making people see things that are not real and appearing and disappearing without being detected.
Innocence is another theme that is explored at length in the story, through the character of Christine in particular. Christine's childhood has been idyllic, and she has been raised by her father to believe that the world is a gentle and welcoming place. Her relationship with Raoul is presented as equally unsullied, untouched by the harsh trials of reality. The innocence of Christine's life is magnified in contrast to the tortured existence of the Phantom.
Motifs that occur throughout the story include the mask, music, and the element of horror. The mask in particular develops the theme of false appearances, concealing the true nature of the Phantom. Music also promotes the theme, with the Phantom presenting himself as the "Spirit of Music", and using this gift to make him seem angelic in Christine's eyes. Elements of horror are also present as a recurring motif, creating an air of mystery and illusion