Long ago, before humanity became thinking and responsible, the hammer of Thor was stolen by the giant Thrym. Thor's hammer represents power not only of destruction but also of creation, including the power to procreate: hence Mjollnir is the symbol of marriage. Loki, agent of the gods and spokesman for the giants, is sent by Thor to find the hammer and forthwith borrows Freya's "feather-guise" and sets out to locate the irreplaceable emblem of creation. Read more
The Lay of Thrym
1
Wielder Thor Awoke angry missed his hammer mighty thunderer, ruffled his mane and red whiskers, son of Earth took to searching about.
2
These words uttered Thor first speaking: 'Hark you, Loki, hear what I say, nowhere to see neither on Earth nor in high heaven; hammer is stolen!