About the Nazca Lines, Paul Devereux argues that they are walking tracks, and that their pattern mainly reveal the religious beliefs of the Kogi Indians around sacred roads. In his 2003 book "Fairy Paths & Spirit Roads", Paul Devereux studied many ley lines worldwide and concluded that these linear features are essentially «paths of spirits». He led the Dragon Project for 10 years and admitted that there are places of high radiation where some participants experienced powerful and vivid hallucinatory episodes of spirit-like visits.