There is a podcast about swedish folklore called "När man talar om trollen" - "Speak of the devil" and at the moment I'm on an episode about snakes.
It's long known that snakes has a big part of nordic folklore and norse mythology but I also learned that snakes was a big part of everyday life in several countries.
Snakes could either be dangerous beasts or give wisdom to humans. One could get wisdom by cooking a snake in a pot and eating it's flesh. It was also common to use grinded snake powder as medicine for different remedies.
During the pre-christian times there was a form of snake cult with pictures or statues of snakes drinking breastmilk. People generally believed snakes to drink milk from cows and served them milk from a plate. Much like how we bring milk to hedgehogs today.
In baltic countries it was believed that snakes inhabitated souls of the dead and was to be treated with respect. Mistreating one was considered a bad idea since said snake could be a dead relative. Part of showing respect was to bring milk to them as well. Generally having a snake around was considered a good sign and placing a dried one close to the front door was considered good luck.
Marthin Luther wrote about something called "husormar" - house snakes which lived among humans, shared porridge and milk with humans or lived in craddles. They were seen as house gods that brough good luck.
The swedish saint Heliga Birgitta - Holy Birgitta wrote about "tomt ormar" - garden snakes, several times and forbid people to bring milk to them. She also claimed to have witnessed people having them inside their houses, in the garden or in the barn. The custom of bringing out milk is also very similar to how people used to bring milk to "hustomten" who is sort of a swedish version of house brownies. A creature that took care of the house hold or bring chaos if the house owners anger him in any way. Some theory says that the house snake or garden snake was later on replaced or changed into hustomten as christianity spread through the nordic countries and all over europe.
The view of snakes as good signs shifted into something bad as they are commonly treated with negative traits in the bible. Even today they are associated with dark themes and are often lumped together with dark magic, lies and trickery.
