For those who need a memory jog or a reference point to make a distinction between the end of the book and the end of the movie, here are a few paragraphs from the end of the novel.

DISCLAIMER: The paragraph below is copied and pasted directly from the novel by Gaston Leroux. The copyright would be his, except that it has apparently passed into the public domain over time. (Does that mean we all own a little tiny piece of it? Hmmm...) Anyway, though I own a copy of the book, I don't own the rights to any of it, including the paragraphs I reproduce here. Further, I don't own the characters. Finally, I'm working with the characters as Leroux described them. Any similarity to any of the movies or musicals bearing the same title or to the novel which was inspired by the novel referenced above is unintentional and purely coincidental—but please inform me of it so I can correct it if I need to!

(The original Leroux follows:)

The monster resumed his mask and collected his strength to leave
the daroga. He told him that, when he felt his end to be very
near at hand, he would send him, in gratitude for the kindness
which the Persian had once shown him, that which he held dearest
in the world: all Christine Daae's papers, which she had written
for Raoul's benefit and left with Erik, together with a few
objects belonging to her, such as a pair of gloves, a shoe-buckle
and two pocket-handkerchiefs. In reply to the Persian's questions,
Erik told him that the two young people, at soon as they found
themselves free, had resolved to go and look for a priest in some
lonely spot where they could hide their happiness and that,
with this object in view, they had started from "the northern
railway station of the world." Lastly, Erik relied on the Persian,
as soon as he received the promised relics and papers, to inform
the young couple of his death and to advertise it in the EPOQUE.

That was all. The Persian saw Erik to the door of his flat,
and Darius helped him down to the street. A cab was waiting for him.
Erik stepped in; and the Persian, who had gone back to the window,
heard him say to the driver:

"Go to the Opera."

And the cab drove off into the night.

The Persian had seen the poor, unfortunate Erik for the last time.
Three weeks later, the Epoque published this advertisement:

"Erik is dead." (p. 250-251)

FINALLY--one LAST note: This is the version that was re-posted on 4/13/2008. There are not too many differences between it and the version I originally posted back on 3/23/2008, but I have corrected typos and added a few more small details.

Therapeutic by Bleeding Heart Conservative

So he resumed his mask and entered the carriage to return to the Opera to die, and that, the Persian thought, was the last he'd see of him. Nearly three weeks later, he received the papers and relics Erik had promised to send and advertised the death simply in the Epoque as he had promised he would. It didn't occur to him to wonder how Erik had managed this. Though Erik had promised to send "when he felt his end to be very near at hand" which would seem to preclude delivering of that nature, or even hauling it to the surface, the Persian had known Erik long enough to consider him capable of nearly anything. He did not return to the opera house to verify the death. Whether the girl—Christine was her name—had read the advertisement he published as he had promised the Persian did not endeavor to determine, and whether she returned with intentions of fulfilling her promise to bury the body of her teacher and tormentor he cared still less to discover. He had done as he had promised. Christine had promised Erik she would take care of the details pertaining to burial, and the daroga had no reason to doubt that she would keep her word. Nevertheless, the simple fact remains that the body was not buried.

This was, however, not negative in the least, as little good can come of burying a body that is not yet dead, regardless of how much it may look so. No, indeed, despite his wish and his prediction, Erik did not die of his love for Christine, though he looked as though he had. Those who had described his features as looking like a dead man's skull might have been much amazed to see how much more so it was true now, and those who had previously remarked that his coat hung on a skeleton frame might consider his former physique to be quite well filled-out compared with the shriveled and shrunken shape that was what was left of the once-dreaded Opera Ghost. And anyone entering the dark recesses of the Opera and encountering these shriveled remains would have been met with a sight that far exceeded the fearful descriptions that had been made over the years of the Phantom, for in the previous years, contrary to what others might have thought, Erik had indeed made quite a show of himself and taken a great amount of time with his appearance.

It is true there was not much he could do about his face, which problem he solved of course, with the mask. He had, however, taken care to dress in the most formal of clothes, as though it were perpetually opening night, even during the day. His black coat was always clean and appeared to have been pressed. He often wore a stylish cape and always had his hair—although it was not his natural hair—neatly combed back from the edges of his perfectly placed mask of the purest white or the blackest ebony, the surface of which he had sculpted and polished from the most sensuous of materials. That is to say when he was not out to be deliberately fearful, he dressed the perfect gentleman and acted the same. Of course, he made other appearances as well, the most famous—or infamous, shall we say—was of course, as "the Red Death stalking abroad" the night of the masquerade ball. Even in endeavoring to be decidedly horrific, however, he had taken the greatest of care with his costume, making his death's head mask exquisitely and decorating his red cape spectacularly in gold trim.

After the final departure of Christine, however, he sunk into a depressive state that exponentially dwarfed his former grief at his isolation and her potential abandonment of him. As there were no mirrors in his abode, and there was no longer anyone to attempt to impress, he saw no point in carefully masking himself. He further saw no reason to pay the least attention to his clothing, his hair, or his health with special emphasis on his health, as he had positively determined to die. Yes, he had determined to die, but he had not the resolve to act upon his own life, and so he teetered precariously on the edge of death, caring nothing for himself or anyone, thinking only of his sorrow. He ate nothing, drank little, composed not at all; there was no more joy in music for him. When he was sure the end was near, he crawled into his coffin and attempted to content himself with the thought that at least he was in not only the proper attire but also the proper fixture in which to be easily buried. It did not occur to him to consider the state of those clothes, to debate himself as to whether he should be masked and if so how, or to wonder whether Christine would keep her promise. He merely lay down, too exhausted now even to cry, and waited to die.

But once again, he was disappointed.