It's amazing how quickly a story can form and people will believe it to be true! The way I explain this to others is using the story of the sword in the stone. Merlin placed the sword in the stone and then told a few people a legend that the stone had been there for a long time waiting for the right person to come along and remove it, which would restore magic within Albion. This then got around the city and everyone tried to remove it. Merlin helped Arthur to remove it by using his magic and the fun began! People will tell you what they want to be true - if it gets told enough it then becomes a 'truth'.