Does Paritta/Sutta really have magical power?
In AN 4.67, the Buddha allowed the monks to use the paritta to protect themselves from harm. Notice Ven. Thanissaro's note:


  "This is one of the few protective charms mentioned in the Pali canon and specifically allowed by the Buddha for monks to use (another charm, also allowed to the monks, is contained in DN 32). Note that the power of the charm is said to come, not from the words, but from the mind of good will with which they are said. It thus differs from charms taught in later forms of Buddhism, where the words themselves are said to contain power."