Have you heard about the terms 'dissociative identity disorder (did)' and 'alter ego'?
Well, these terms have been used by science to explain what most people would see, hear and call spiritual/magical possession. As most will agree, the possession of the person (let's call him the victim) is of the soul. Let's not forget that it starts with the mind, when it has left the state of well-being.
DID is a state of which a person (singular entity) bears more than one person in his mind (plural entity). He possesses more than one personality i.e acts totally differently like different individuals at seperate times. He could be aware, but most times he is not.
Alter ego is a situation where by a singular personality over-shadows the other(s). That particular personality takes over him (as the name implies, alters his person) like a dominant trait and he acts in accordance. And at this point it gets really scary. The victim here loses his own personality like one loses his mind, and behaves all different.
These situations occur when the victim had a troubled childhood with terrible experiences. They are triggered when similar events or occurrences come into play in a later part of their life, that brings back a reminiscence of those better forgotten memories. DID also occurs when one tries to imitate the actions and behavioural traits another person and somehow manages to fit well into the play, making it a habit or way of life. In time he/she gradually loses a part of himself/herself.., and if not recognized and treated in time it may lead to the severe case; an alter ego.
If a persons mind is infected, it affects his psyche and mental judgement, even his emotions to a large extent. And when it does, it goes a long way to affect his soul. What the heart thinks, it acts upon.

We are advised not to take in already expired products into our body. These products range from canned foods (all kinds of preserved food), drinks to drugs. We hear adverts on tv concerning this, campaigning on the poisonous effects they might have on our functioning system. But then, what about expired poisons? We know very well poisons are harmful to us in varying degree. To what extent do you know an expired poison to be harmful? Does it still keep its characteristic red eye even after expiring? Is a poison more dangerous when expired or less?