"What harm can the devil cause to the living? There are few books on the subject and a lack of common language. I will now attempt to define the words that I will use in this book.
Ordinary activity. This is "temptation", which is the most common activity of the demons, and it is directed against all men. When Jesus allowed Satan to tempt him, he accepted our human condition. I will not talk about this common diabolical endeavor, because the purpose of this book is to highlight Satan's "extraordinary activity", which can take place only if God so allows.
This second category can take six different forms:
1. External physical pain caused by Satan. We know of this from many lives of the saints. We know that Saint Paul of the Cross, the Curé of Ars, Padre Pio, and many others were beaten, flogged, and pummeled by demons. This external form of persecution does riot affect the soul; therefore with this type there has never been the need for an exorcism, only for prayers. Here I will dwell only on the other types of actions that directly affect exorcists.
2. Demonic possession. This occurs when Satan takes full possession of the body (not the soul); he speaks and acts without the knowledge or consent of the victim, who therefore is morally blameless. It is the gravest and most spectacular form of demonic afflictions, and it attracts the attention of producers of movies such as The Exorcist. According to the Ritual for exorcisms, some of the signs of possession include: speaking in tongues, extraordinary strength, and revealing the unknown. The man of Gerasa is a clear Gospel example of possession. To fix a set "model" for demonic possession would be a serious mistake; the affliction runs the gamut of symptoms and severity. For instance, I have exercised two totally possessed persons who remained perfectly still and silent during the exorcism. I could cite many other examples and as many different symptoms.
3. Diabolical oppression. Symptoms vary from a very serious to a mild illness. There is no possession, loss of consciousness, or involuntary action and word. The Bible gives us many examples of oppression; one of them is job, He was not possessed, but he lost his children, his goods, and his health. The bent woman and the deaf and dumb man who were cured by Jesus were not subject to total possession, but there was a demonic presence that caused physical discomfort. Saint Paul was most certainly not possessed by a demon, but he had a demonic oppression that caused an evil affliction: "And to keep me from being too elated by the abundance of revelations, a thorn was given me in the flesh, a messenger of Satan, to harass me" (2 Cor 12:7). There is no doubting the evil origin of the affliction.
While possessions are still relatively rare today, we exorcists run into a great number of people who have been struck by the devil in their health, jobs, or relationships. We must make it clear that to diagnose and heal an oppression-related illness is not any easier than to diagnose and cure a person afflicted by full possession. The degree of gravity may be different, but the difficulty of the diagnosis and the amount of time involved in healing are the same.
4. Diabolic obsession. Symptoms include sudden attacks, at times ongoing, of obsessive thoughts, sometimes even rationally absurd, but of such nature that the victim is unable to free himself Therefore the obsessed person lives in a perpetual state of prostration, desperation, and attempts at suicide. Almost always obsession influences dreams. Some people will say that this is evidence of mental illness, requiring the services of a psychiatrist or a psychologist. The same could be said of all other forms of demonic phenomena. Some symptoms, however, are so inconsistent with known illnesses that they point with certainty to their evil origins. Only an expert and well-trained eye can identify the crucial differences.
5. Diabolic infestation. Infestations affect houses, things, or animals. This book will only mention the topic. I merely want to state that I will never use this term when I refer to persons. I will always talk about possession, oppression, and obsession.
6. Diabolical subjugation, or dependence. People fall into this form of evil when they voluntarily submit to Satan. The two most common forms of dependence are the blood pact with the devil and the consecration to Satan.
How can we defend ourselves from all these evils? A strict interpretation of the Ritual confines the use of exorcisms only to instances of true possession. However, as I stated before, the current Ritual fails to address many occasions in which an exorcist diagnoses an evil influence. In all cases when there is no possession, the usual means to obtain grace should be sufficient. These means are prayer; the sacraments; almsgiving; leading a Christian life; pardoning offenses; and soliciting the aid of our Lord, Mary, the saints, and the angels. I will now say a few words about the angels. I gladly end this chapter on the devil, Christ's adversary, by speaking about the angels. They are our great allies. We owe them a great debt, and it is a mistake to mention them as rarely as we do. Every one of us has a guardian angel, most faithful of friends twenty-four hours a day, from conception to death. He unceasingly protects us, body and soul, while we, for the most part, never think about him. We also know that each nation has its particular guardian angel and, probably, every community and family, although we are not certain on the two last points. We know, however, that the angels are a multitude, and their desire to help us is much greater than Satan's desire to destroy us."
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