A stranger offers the gods an unbreachable wall around their stronghold - in a single winter. His price is outrageous. How the gods almost miscalculate, Loki turns into a mare, and in the end the most famous horse in all mythology is born.
After the battles of the early days Asgard stands undefended, and the gods long for a wall no giant can cross. Then a builder comes and makes an offer: he will raise the whole fortress wall, and in only three seasons. But his wage is boundless. He demands the goddess Freyja for his wife, and with her the sun and the moon out of the sky.
The gods take counsel and hesitate. Such a price would be the ruin of the world - without sun and moon no light, without Freyja no joy. Yet the temptation is great. In the end it is Loki who advises the bargain, but with a condition: the builder shall have only a single winter, not three seasons, and he may take no one to help him. The deadline seems impossible, and the gods feel safe.
The builder accepts the harsh condition, asking only that he be allowed to use his horse for the work. The gods permit it. And here lies their mistake. The stallion Svadilfari is no ordinary beast. Night after night he hauls in enormous boulders, twice as much as his master can hew. The wall grows at an alarming pace.
Three days before the start of summer the work is almost complete. Only the gateway is still missing. The gods realise they are going to lose the bargain - and with it Freyja, sun and moon. Panic breaks out. They look for someone to blame, and he is quickly found: Loki, who had advised the deal.
The gods threaten Loki with death if he does not avert the disaster. So Loki reaches for his tried and tested means, transformation. In the night he becomes a beautiful mare and lures Svadilfari away from the work. The stallion breaks loose and chases after the mare, deep into the forest. The builder runs after them in vain.
Without his horse he cannot finish the last stones in time. The deadline passes, the gateway stays open, the bargain has collapsed. In his rage the builder now shows his true nature: he is a mountain giant in disguise. That voids the agreement anyway, for the gods would never have promised Freyja to a giant. Thor is called, and with one blow of his hammer he slays the deceiver.
The story has a strange sequel. Loki, who had run off with the stallion Svadilfari as a mare, becomes pregnant. He gives birth to a foal - a grey horse with eight legs, swifter than any other beast. It is called Sleipnir and becomes Odin's mount, carrying him over land, water and into the world of the dead.
The best of horses is Sleipnir, it belongs to Odin; it has eight legs.after the Prose Edda, public-domain translation tradition
So an attempted swindle ends with the birth of the noblest horse in the world. The Norse did not shrink from placing their gods in such entanglements. Loki as the mother of an eight-legged foal - that is grotesque, comic and mythic all at once.
The tale does not stand alone. In many cultures there are legends of the superhuman builder who raises a structure in impossible time and demands a terrible wage for it - often a soul, a child or the life of the master. Usually he is cheated of his reward in the end by a trick. The Norse version adds its own figures to this wandering motif: cunning Loki, hammer-wielding Thor and a marvellous eight-legged horse.
The story stands in full in Snorri's Prose Edda, Gylfaginning 42: the builder, the deadline of one winter, the price of Freyja, sun and moon, Loki's advice and rescue, Thor's killing blow and the birth of Sleipnir. The Voluspa (stanzas 25 to 26) alludes to the gods breaking a treaty. Public-domain tradition of the 13th century.
The Voluspa names only the broken oath, not the full sequence - the rounded narrative is Snorri's work. Morally the gods do not come off well: they strike an impossible bargain and settle it by deceit. The superhuman builder is an international legend type; Sleipnir's strange parentage is the distinctive Norse addition.
Loki · Thor · Sleipnir – Odin's steed · The Norse pantheon · Bifröst – the rainbow bridge.