To quote his own words, in his Memoirs: "This moonshine about the Opera ghost in which, since we first took over the duties of MM.

Poligny and Debienne, we had been so nicely steeped"-- Moncharmin's style is not always irreproachable--"had no doubt ended by blinding my imaginative and also my visual faculties.
It may be that the exceptional surroundings in which we found ourselves, in the midst of an incredible silence, impressed us to an unusual extent.

It may be that we were the sport of a kind of hallucination brought about by the semi-darkness of the theater and the partial gloom that filled Box Five.

At any rate, I saw and Richard also saw a shape in the box.

Richard said nothing, nor I either.