If hallucination means seeing ghosts and apparitions, that is, something that is not there, reverse hallucination means not seeing what is there. Thus Norbert Hanold the archeologist, obsessed with the Greek statue Gradiva who walks with a particular gait, cannot see the living woman Zoe Bertgang: "Hanold, who... had the gift of "negative hallucination", who posessed the art of not seeing and not recognizing people who were actually present."