Why do people still practise dowsing for water?
Dowsing - the art of trying to find sources of water and other materials below the ground using nothing but a twig or rod as an apparatus - is something that has been attempted for centuries.
But despite the lack of convincing scientific evidence behind the practice, in the 21st Century there are still many people who claim to have had success with it - and even people who make careers out of it.
Experiments carried out under controlled conditions to test its accuracy have suggested that it only seems to "work" when the dowser has some unconscious knowledge of where the source is.
Other experiments looking at why the rods seem to move of their own accord when water is supposedly struck, have suggested that this is the result of muscle movements caused by subconscious mental activity - the same phenomenon that has been shown to lie behind movements of objects on a Ouija board.
But John Baker from Kent is one of those who is regularly employed by companies and private individuals to dowse for water and other materials. He says he discovered his ability in 1993 - and says that "dowsing is an art not a science. As in all things, there is no guarantee of success."
BBC News went to meet him.
Video journalist: Tom Beal
Real Time is a series for the BBC News website in which ordinary people tell their own extraordinary stories.