In the Slavic pantheon, the God Kupala (Kupailo, Kupaila) is the embodiment of the energy of sunlight. He is inextricably linked with his mother, a swimmer, but most importantly, his wife Kostroma, who, as it turned out after the wedding, was his half–sister.
Kupala's father is the great Slavic God Semargl. He was the permanent guardian of the world of Light, but he could not resist the call of his beloved Swimmer and one day, on the day of the summer solstice, he left his post to meet her. It was because of the love of Semargla and the Bathing Suit, from the moment they met, the nights began to get longer so that the lovers could stay together longer.
As a result, Kupala and Kostroma were born, again on the day of the summer solstice. The god Perun was very happy with his brother's happiness and gave the newborns a piece of his power, putting it into a fern flower.
