On the other hand, the idea that I might be caught by Erik suddenly made me think of the death of Joseph Buquet.

I did not wish to jeopardize the advantages of so great a discovery which might be useful to many people, "to a goodly number of the human race," in Erik's words; and I left the cellars of the Opera after carefully replacing the stone.
I continued to be greatly interested in the relations between Erik and Christine Daae, not from any morbid curiosity, but because of the terrible thought which obsessed my mind that Erik was capable of anything, if he once discovered that he was not loved for his own sake, as he imagined.

I continued to wander, very cautiously, about the Opera and soon learned the truth about the monster's dreary love-affair.
He filled Christine's mind, through the terror with which he inspired her, but the dear child's heart belonged wholly to the Vicomte Raoul de Chagny.

While they played about, like an innocent engaged couple, on the upper floors of the Opera, to avoid the monster, they little suspected that some one was watching over them.

I was prepared to do anything: to kill the monster, if necessary, and explain to the police afterward.