Why is the sky blue? C'mon, tell me. You're going to probably tell me that it's because it absorbs all other colours and reflects blue light. But why is this so? This is because of the vibrations of the electrons. Why, you may ask? The answer is a simple five-letter word. Magic. Yes, magic. When people can't describe something, they simply describe it as magical. Imagine, the ancient times and the medieval ages, when people didn't know very much. So, practically everything was magic. And it wasn't just magic. Things that are born of magic. Things both benevolent and monstrous. Things like fairies and unicorns, as well as werewolves and manticores. But the most famous of them: DRAGONS!
Now, we all know what dragons are. Those giants, scaly things that breathe fire and guard treasures and towers that have virgins in them. But why virgins? Number one, it wouldn't be very nice for the knight. Number two, virgins symbolize innocence. Dragons are like protectors of the innocent (except when they eat them).
Dragons are symbols of the devil. The dragon is a symbol of the devil because of the way Christians were treated in the Roman Empire. The Christians considered the Roman Empire hell and the emperor Satan (this is why 666 is considered the devil's number). What did the Roman emperor do to Christians? They used to throw them to the animals. This is why they thought dragons had "belly of a crocodile" and things like that. They basically combined the parts of the animals that they feared together to get one big fear instead of many little fears. That's one reason why the Chinese think that dragons are benevolent. They weren't ever thrown to animals.
Now, let me expand on Chinese dragons. They are used to explain rain, storms and clouds. As I said before, they knew a lot about a lot, and a lot about nothing. So they made dragons to explain things. It's that simple.