The celebration of Midsummer's Eve was from ancient times linked to the
summer solstice. People believed that midsummer plants had miraculous healing powers
and they therefore picked them on this night.
Bonfires were lit to protect against evil spirits which were believed to roam freely
when the sun was turning southwards again. In later years, witches were also thought
to be on their way to meetings with other evil powers.
Midsummer's Eve is a public holiday in Finland, Latvia.