In Norse mythology, Gleipnir is made from six impossible ingredients.
The Prose Edda lists the sound of a cat’s footfall, a woman’s beard, the roots of mountains, bear sinews, fish breath, and bird spittle. These ingredients are paradoxical or unavailable in ordinary experience, which emphasizes that Gleipnir is a magical binding rather than a normal chain.
The dwarfs create Gleipnir at the gods’ request after earlier restraints fail to hold Fenrir. Its appearance is described as remarkably light and soft, yet Fenrir cannot break it. The wolf suspects treachery and demands a pledge before agreeing to the test; Týr provides that pledge by placing his hand between Fenrir’s jaws.
The six ingredients are often remembered incorrectly as symbolic objects or as parts of a metal fetter. The myth instead presents them as fantastical substances whose disappearance explains why certain things no longer exist in the natural world.