There must be many ways for a person to be obsessed, in the book, Action and Reaction, by Francisco C. Xavier, dictated by the spirit Andre Luiz, there is an example of one method used to cause an innocent person to become obsessed.
The definition of obsession is:
“The domination of one’s thoughts or feelings by a persistent idea, image, desire, etc.” 
encounters a woman who ask that he and his friends assist her to help her son. She tells them that her son, Luis, is being obsessed because of the wrongs of his father.
Luis is now grown into a man with a wife and children. His father murdered his two uncles so only he would be left with the inheritance. With the father dead and out of the uncles grasp in the spirit world, the two are concentrating on destroying their nephew’s life. All out of revenge.
Andre Luiz journeys to the house where he finds it filled with miserly spirits. Spirits who are themselves obsessed with the material world and treasure. These poor spirits haven’t been able to leave the lower zone because of their inability to free themselves of their desire for riches on earth. They haven’t yet learned to look up and follow the path of love and service to others.
Andre and company wander around the house. They spot the son, freed from his physical body at night, admiring the stacks of money in his office, there they meet the two uncles. After a brief conversation with the two malefactors, Silas, Andre’s team leader summarizes the situation:
“What you’ve said leads us to believe that, besides his sickly attachment to precarious human wealth, this man,” and he pointed to Luis, who continued to seem fascinated with the stacks of currency in the over-stuffed drawer, “also suffers the pressure of other minds as delusional as his own in the illusions of material possessions. In this case, the sick desire that has seized him has increased to the maximum.”
One of the uncles, Leonel, proudly acknowledges what has just been said and like all criminals, he can’t wait to describe exactly how the deed was accomplished:
“Yes, we learned in the schools for avengers that, besides our ordinary, immediate desires at every phase of life, we all possess a central desire or basic theme in our innermost interests. Therefore, besides the normal thoughts that bind us to our daily routines, we more frequently emit the thoughts that originate in the central desire that characterizes us. These thoughts eventually comprise the dominant reflection of our personality. This makes it easy to perceive anyone’s nature on any plane just by analyzing their occupations and places of preference. Thus, cruelty is the reflection of the criminal, covetousness the reflection of the miser, defamation the reflection of the slanderer, sarcasm the reflection of the cynic, and anger the reflection of the disturbed person, just as moral elevation is the reflection of the saint.” 
What an easy mark most of us would be! I quickly recognized my dominate theme as a cynic, with sarcasm flowing from my thoughts and tongue. I have tried to improve, but a quick sarcastic remark is often the first impulse that comes to mind.
Clearly, I need to meditate and explore what exactly is my “central desire” and my “basic theme”, so I may focus my energies on the good and not be influenced to exhibit undesirable behavior.
Next, Leonel, discusses the exact process to leverage what is already inside us:
“Once we discover the reflection of the individual we want to rectify or punish, it is very simple to overwhelm the person with unceasing stimuli, reinforcing the impulses and images already in his mind and creating new ones to superimpose over the old ones, thereby continually feeding his mental fixation. With this objective in mind, all we have to do is bring the pernicious individual we want to correct into contact with others that adapt to his manner of feeling and being, especially when we ourselves don’t have the time to create all the appropriate mental screens through hypnotic procedures. Using such processes, we can easily create and maintain his psychic delirium or obsession, which is nothing more than an abnormal state of the mind that is dominated by the excess of its own creations pressing in on the sensorial field. This can be infinitely added to by the direct or indirect influence of other incarnate or discarnate minds that are attracted by their own reflections.” 
Lastly Leonel tells the group:
“Everyone is tempted on the outside by the temptation they feel on the inside.” 
Andre and his comrades are amazed at the succinct explanation. Take the mental state of the victim, use it, magnify it by planting even more of the same back into the thought generator and you have an effective ever-increasing feedback loop.
Our brain picks up more than we know. Our mind also radiate thoughts to the world. We are a delicate instrument which must be kept in harmony at all times.
Modern stress opens us up and makes us vulnerable to outside influences upon our feelings. Guard against playing the same thoughts over and over again in your mind, they can be used against you.
If you find yourself pondering negative contemplations take a time out and slow down. Meditate and use your faith to forgive and forget, focus your energy on positive endeavors. Just like our physical body, which we must take an inventory at times to insure our good health, we should do the same mentally.
Take stock of what motivates you. Examine your desires and plans for the future. Moderate your aspirations and go forward with your plans using only honorable intentions and all shall be right.
To understand you own destiny and the types of trials you may have to journey through, I recommend you read my book, Explore Your Destiny – Since Your Life’s Path is (mostly) Predetermined. The book covers the different types of areas in the spirit realm and the types of spirits which reside side by side with us.
Brian Foster has a BSCS degree and a MBA. He has worked in R&D for medical device corporations and in IT for large financial institutions. Brian Foster has a blog at http://www.nwspiritism.com.
Dictionary.com. (2015, May 22). Dictionary.reference.com/obsession. Retrieved from Dictionary.com: http://dictionary.reference.com/browse/obsession
Xavier, F. C. (2010). Action and Reaction. Brasilia (DF), Brazil: International Spiritist Council.
 Dictionary.com, Obsession, n.d., http://dictionary.reference.com/browse/obsession (Accessed May 22,2015)
 Xavier, F.C. Action and Reaction, EDICEI, p. 105
 Xavier, F.C. Action and Reaction, EDICEI, pp. 105-106
 Xavier, F.C. Action and Reaction, EDICEI, p. 106
 Xavier, F.C. Action and Reaction, EDICEI, p. 106