Before the Christian era, the Slavs believed that the change of seasons was a struggle between Jarilo, the god of vegetation, fertility and springtime, and the evil spirits of cold and darkness. People believed that they had to help Jarilo fight against winter and bring in the spring. The most important part of Shrovetide week (the whole celebration of the arrival of spring lasted one week) was making and eating pancakes. The hot, round pancakes symbolized the sun. The Slavs believed that by eating pancakes, they got the power, light and warmth of the sun. The first pancake was usually put on a window for the spirits of the ancestors. On the last day of Shrovetide week some pancakes and other food were burnt in a bonfire as a sacrifice to the pagan gods.