During the Medieval period dragons were typically thought as a evil fire-breathing, horned, muscular, with a very strong tail. A dragon's blood was usually had magical properties, for example in the opera Siegfried the dragon’s blood allowed Siegfried let him understand the language of a forest bird. Dragons were protecting cavern or a castle filled with some sort of treasure. Some of the more popular dragons were often described as illuminating the air. This was taken from the Christian writers as a metaphor for a Lucifer as the “angel of light”.
