Throughout the story, the Phantom is often associated with mirrors and reflections, which suggest his divided self and his fascination with appearances. He lives in a hidden lair beneath the Paris Opera House, where he surrounds himself with mirrors, creating an illusion of a vast and opulent space. This reflects his attempts to create an idealized version of himself, as he lacks confidence in his true appearance and is afraid to be seen by others.
The Phantom also uses the mirrors to spy on Christine Daaé, the young singer he becomes infatuated with. This reflects his desire to possess her and to make her an extension of himself. The mirrors symbolize the way he controls and manipulates Christine, creating an illusion of their union that is ultimately false and destructive.
Additionally, the mirror becomes a symbol of the Phantom's confrontation with his own mortality and his fear of aging. When he is injured and loses his mask, the Phantom stares at his reflection and sees the true horror of his own face, which leads to his eventual demise.
Overall, the mirror in Phantom Opra symbolizes the Phantom's internal conflicts and his struggle for acceptance and identity, reflecting the themes of duality and self-deception that are central to the story.