Nordic mythology

The creation
According to the myths, before the world was created there existed only Muspelheim, the world of fire, and Niflheim, the world of ice. The warm air melted the ice and out of the water grew the giant Ymir and the cow, Audhumbla. Ymir woke and drank Audhumbla's milk. Whilst he drank, the cow Audhumbla licked on a salt stone. On the first day after this a man's hair appeared on the stone, on the second day a head and on the third day an entire man emerged from the stone. His name was Búri and with an unknown giantess he fathered Bor, the father of the three gods Odin, Vili and Ve. These three gods created the universe from Ymir’s body.

One day when the gods were walking the earth they found two tree trunks. They transformed them into the shape of humans. Odin gave them life, Vili gave them mind and Ve gave them the ability to hear, see, and speak. The gods named them Ask and Embla and built the kingdom of Middle-earth for them and to keep the giants out the gods placed a gigantic fence made of Ymir’s eye-lashes around Middle-earth.

The universe
The many worlds of the universe are connected through the giant Tree of Life, the Ash tree Yggdrasil.

The gods, the Æsir, live in Asgaard, the home of the gods at the top of the tree. Odin is the king of the Æsir and he lives in the house of Valhalla, where the dead warriors feast in the afterlife. The humans live in Middle-earth at the middle of the tree. Middle-earth and Asgaard are connected with the rainbow bridge Bifrost. At the foot of the tree, the three Norns (goddesses of fate) spin the threads of each individual life.

In the underworld Hel a snake is chewing one root of Yggdrasil. The Jötnar (giants) live in Jotunheim, which lies at the end of the second root of Yggdrasil. The third root goes all the way to icy Nifleheim. The gods and the humans are always threatened by the evil and cunning Jötnar – a conflict that will ultimately end in the destruction of the world, Ragnarok. The fire giants of Muspelheim awaits this day, as they are foreseen to break the Bifrost during the battle.

Order vs. chaos
The dualism that exists is not good vs. evil, but order vs. chaos. The Æsir and their allies represent the natural forces of cosmic order, whereas the Jötnar represent the natural forces of destructive chaos. The celebrations of the natural order of the change of the four seasons fall within the realm of the gods and the humans and are also reflected in the deep connection to nature, that we find everywhere in the myths.

The summer solstice celebrations can thus be seen as stemming partly from these ancient beliefs.

Sources: Wikipedia da/en