On the Dragon
Introduction by Juris Lidaka
Bartholomew says: "The dragon is the largest of all serpents, as Isidore says [Etymologies 12.4]. The Greeks call it “dragon,” since often, when it has been dragged out of its cave, it is borne into the air, and the air is moved because of it; similarly the sea rises at its arrival. It is crested, with a small face, and it draws its breath through narrow tubes, and stretches and sticks out its tongue. It has sharp serrated teeth, but its strength is not in its teeth but rather in its tail, and it does more harm by beating than by stabbing. It does not have as much poison as other serpents, since poisons are not necessary for it to bring death upon anything, since if it binds anything, it kills it. Therefore even an elephant is not safe because of the size of its body, for it hides around the paths where elephants walk, ties and knots its tail around their legs, and destroys and kills them by suffocation."
Everyone's favorite mythical beast
What is it about dragons that makes them so attractive to people in many lands and places? Some modern people may insist that dragons are real, that they helped people achieve civilization, and that they are in hiding now because people are too materialistic and not spiritual enough. But elsewhere dragons have been viewed as evil, like Grendel from Beowulf. He finds an old treasure hoard, claims it as his own, and then burns the countryside when a single goblet is taken away.
Bartholomew's Roman Catholic, English heritage contained many stories about dragons. In addition to Grendel, you probably have heard of the legendary story of St. George and the dragon 
. There is also St. Margaret of Antioch , who was swallowed by the devil in the shape of a dragon.
Medieval dragons did not necessarily breathe fire. Grendel from Beowulf does, but the dragon in the medieval bestiary does not.
Bartholomew tries to find a naturalistic explanation that will reconcile the two traditions: it is not that the dragon breathes or spits fire, but that the dragon's venom may set the air aflame. Although he says that Pliny gives this information, it is not in the Historia naturalis and Pliny actually says “The dragon is a serpent destitute of venom” (HN 29.20).
Who has not heard of medieval maps with warnings about certain areas that “Here There Be Dragons”? As with so many stories, this one is not true. The earliest object with this warning on it is the Lenox Globe dating from after the Middle Ages (1503-7).
It may have been just a joke against those bad, old middle-evil times -- a prejudice we still hang on to today.