I was reading R.Jordan's "The Wheel of Time". I've faced the following sentence: "Everything else in the room was shown true, but not him.". I only have some guesses how to understand it.
Some previous sentences to make it more clear:
Strange oval stones made the fireplace; they just looked like stones, wet-slick despite the fire, when he looked straight at them, but when he glimpsed them from the corner of his eye they seemed to be faces instead, the faces of men and women writhing in anguish, screaming silently. The high-backed chairs and the polished table in the middle of the room were perfectly ordinary, but that in itself emphasized the rest. A single mirror hung on the wall, but that was not ordinary at all. When he looked at it he saw only a blur where his reflection should have been. Everything else in the room was shown true, but not him.