A hallucination is imagining something that is not there. The most common kinds of hallucination are seeing or hearing things that are not present. A person experiencing hallucination is sure that he is feeling or smelling, or tasting something when he is not.
Hallucinations occur in the mind and are most common in persons who are mentally sick, but normal people who are under great stress or who have high fever may also suffer hallucinations. There are those whose hallucinations might be dangerous to themselves and to others. Such people believe that they are being hounded by others, and must, at all costs, run away from imminent danger. They hear voices urging them to run away from home in order to avoid being hurt by an enemy. Their life is constantly dictated by the voices that they hear in their head. The world of reality, as far as they are concerned, is simply non-existent. Generally, the voices that they hear could either be gentle or harsh, depending on their relationships and the nature of their environment. Where conventional reasoning is absent, logic and reality are missing.
There are people who hear voices that are so frightening that they believe what they are hearing. There seems to be no cure for this disease, and there is a great deal of research that is presently in progress. However, there are some potent, psychotropic drugs that help to lessen the hallucinations by relaxing the mind and mitigating the severity of the attacks.
There are different kinds of mental diseases, but hallucinating and hearing voices fall in a category by itself. Those that hallucinate constantly are likely to become homeless. Many times, when they run away from home, there whereabouts become unknown. It is unfortunate that the affliction does not only victimize the sufferer, but also the other members of the family. It is difficult to control the person that keeps hallucinating, and, therefore, at some point in time, families seem to have no other option but to abandon victims of such a mental disease, or confine them in a mental hospital. The former option is most common. We see many homeless people that are huddled on sidewalks, shouting and muttering words that are unintelligible. There is a possibility that their families might have abandoned them, judging from their action and mannerism.
I am personally aware of an incident when a boy ran away from home because he would hear voices urging him to do so. The family could not locate him and have finally stopped looking for him. His whereabouts are unknown.