The stories about David first appeared in a book about the life of David written by a monk called Rhigyfarch (which was written about eight hundred years ago). Rhigyfarch lived five hundred years after David. Some of the stories in his book may not have been true, but the Celtic people loved listening to them. David was one of their great Celtic heroes - a man who lived a holy life and who could also perform miracles. Whether he performed as many as Rhigyfarch writes about is doubtful, but the stories are traditional, symbolic tales of a great religious leader.
Rhigyfarch found some very old books about David in Saint David's Cathedral. Rhigyfarch's father was bishop of St. Davids so he would have spent many hours exploring all the nooks and crannies of the cathedral. When Rhigyfarch found the books they were worn and tattered; many of the pages had been eaten by worms. So Rhigyfarch decided to write his own book about David, using the information from the old books. He wanted people to remember David as a role model, possibly to show the great religious leaders of England that many churches in Wales, England and Ireland were influenced by this great Welshman. David was a man who had helped the growth of Christianity in Wales.