Safety from Vampires!
It’s so reassuring to me that in legends, vampires cannot enter your home unless you invite them! That makes them almost safer than humans! Humans who bear you ill will can smash in through a window, charge through your wall with a chainsaw, and such. Vampires can’t touch you if you’re safe and cozy inside. If a vampire’s standing outside waiting to do you harm, too bad for them! You can even stand right up at the doorway or window and stick your tongue out at the vampire, or bite your thumb at it! You can dance a little jig and insult its vampire prowess all you want, and there's nothing it can do as long as you don't step outside or invite it in. You can just bring out some garlic, have yourself a cup of tea, and sleep peacefully inside until sunrise!
There are lots of ways to protect yourself from vampires. Hang garlic cloves all around your house. Hang up bells. Throw some poppy seeds across your porch. Pour some unbroken lines of salt across entryways, and sleep in a circle of salt. Wrap silver chains around your doors! Hang up a crucifix. Keep some holy water handy.
Why do these things work? Salt is a common protective tool against demons and evil beings of all sorts. It was held as important from even ancient times. It’s essential to humans, has been used in rituals, and used as a preserver, of course. It could keep things from decaying, or at least slow the process. It was soon ascribed with magical powers; the ability to keep evil away.
Garlic was used in many cultures, and much folklore has garlic protecting against all sorts of evil, including werewolves.
Other sorts of plants and leaves like holly and juniper would protect against vampires. Beliefs about different substances that warded off evil were applied to vampire creatures as well. Also, vampires are said to be unable to cross a thicket of wild rose or hawthorn. These are protecting plants against evil, from unknown origins.
Many cultures, including Greek and Chinese, have myths about spirits that cannot cross moving bodies of water. This has been applied to the vampire as well, over time.
Holy water and crucifixes come, of course, from the Christian mythologies about protection from devils and demons. Water blessed by a priest would be destructive to any agent of evil. Crucifixes, the symbol of sacrifice and God’s love, would surely protect from any creature of Satan. Silver may also have some religious connections, but the origin of the silver myth is uncertain.
Mirrors are also stem from religious superstition. Mirrors are supposed to be the reflection of the soul; pure mirrors, backed in silver. Vampires have no soul.
Why bells? Why poppy seeds? Well, demons of all sort had an aversion to the ringing of bells. The sound of bells was loathsome to evil spirits, and so vampires are equally repelled. Poppy seeds, or any sort of small seeds, or anything of that sort, were useful, according to myth, because vampires would have to stop and count every single seed before they could continue. And the hope would be that the vampire would get stuck counting seeds and not notice the time, and then the sun would rise and destroy the creature.