“How is true possession to be distinguished from fraud or the symptoms of disease? The Church prescribes four tests - the language test, the test of preternatural physical strength, the test of levitation and the test of clairvoyance and prevision. If a person can on occasion understand, or better still, speak a language, of which, in his normal state, he is completely ignorant; if he can manifest the physical miracle of levitation or perform unaccountable feats of strength, and if he can correctly predict the future or describe events taking place at a distance - then that person may be presumed to be possessed by devils. (Alternatively, he may be presumed to be the recipient of extraordinary graces; for in many instances divine and infernal miracles are, most unhappily, identical. The levitation of saintly ecstatic is distinguishable from the levitation of ecstatics demoniacs only in virtue of the moral antecedents and consequences of the event. These moral antecedents and consequences are often hard to assess, and it has sometimes happened that even the holiest persons have been suspected of producing their ESP phenomena and their PK effects by diabolic means.)”