Have you ever seen something that wasn't really there? Heard someone call your name in an empty house? Sensed someone following you and turned around to find nothing? Hallucinations don't belong wholly to the insane. Much more commonly, they are linked to sensory deprivation, intoxication, illness, or injury. In some conditions, hallucinations can lead to religious epiphanies or even the feeling of leaving one's own body. Humans have always sought such life-changing visions, and for thousands of…Show more