At the beginning of The Phantom of the Opera, Leroux uses visual imagery of Erik's face to create a sense of intrigue and horror. In Chapter 1, Joseph Buquet describes the "ghost," or the Phantom, as follows:
He is extraordinarily thin and his black coat hangs loosely off his skeletal frame. His eyes are so deep-set that you cannot make out his pupils: all you can see are two big black holes, as in a skull. His skin is stretched over his bone structure like a drumhead, and is not white but an ugly yellow. His nose is almost non-existent when seen sideways; and this absence is a horrible thing to behold. As for his hair, it consists of no more than three or four long dark strands on his forehead and behind his ears.
Here, the reader gets a good sense of the shape, texture, and color of Erik's face. He is "thin" and "skeletal," he has "black holes" instead of eyes, and his skin is tight and yellow. Establishing the visual specifics of his face is essential to the story, which revolves around the crisis of his isolation. Erik's deformity inspires not only perpetual mask-wearing but a lifetime of shadow-like existence. Visual imagery is one of the most important devices used in this first chapter because it allows the reader to understand Erik's source of pain and the story's source of conflict.
The most prominent example of imagery in The Phantom of the Opera is, of course, auditory. In Chapter 10 the narrator describes the Phantom's voice in great detail:
The disembodied voice resumed singing. Never in his life had Raoul heard a voice combining in one breath such extremes, a voice at once immensely, heroically sweet and triumphantly insidious, subtly powerful and powerfully subtle, in short a voice of irresistible potency. There was, in that singing, something definitive and masterful that must, in itself, inspire every mortal who appreciates, loves and makes music. It was a tranquil and pure fountain of harmony from which the faithful could safely and piously assuage their thirst, secure in the knowledge that they were partaking of musical grace.
Words like "heroically sweet" and "subtly powerful" form a well-rounded depiction of the Phantom's voice. The repetitive interplay of opposites, as well as the metaphorical "fountain of harmony" to which his voice is compared, show a range of rhetorical techniques comparable to the Phantom's range of singing talent. Whether or not this is intentional remains unclear; however, the narrator's extensive research and sympathy toward the musically-gifted Erik suggest that the story's form purposefully matches its content. Finally, it is important to note that the Phantom's music often appears to have holy qualities despite his violent and immoral tendencies.
Although Leroux rarely provides a sweeping panorama of the opera house, he does permit insight into its specific qualities through anecdotes about Erik, Raoul, and Christine. For example, in Chapter 12, Raoul and Christine explore its labyrinthine passageways:
And she would lead him up above the clouds, to the splendid chaos of the upper flies, where she loved to make him giddy by scampering ahead of him along the flying bridges among a thousand ropes fastened to pulleys, windlasses and drums, amidst a veritable aerial forest of masts and spars.
The opera house seems very grand and complex. Christine and Raoul use it to play inventive games; they imagine themselves to be "above the clouds" and in a "veritable aerial forest" of equipment. According to Christine, it also contains imaginary worlds. In Chapter 12, the narrator further describes their so-called travels:
the two of them, seated on some worm-eaten stage property, would listen to tales about the Opera as they had listened long ago, in their childhood, to old Breton legends. Forgotten by successive administrations and untouched by palace coups, these people had lived in the Opera House for countless years and had no recollection of the world outside.
Details like "worm-eaten stage property" give a good sense of the age of the theater. Specific moments in the story with great visual imagery provide useful snapshots of the opera house's appearance; although readers never get a complete description of the entire building, its many parts come to life at various stages of the story.