What is the "horn of plenty, in the Land of Heroes: A Retelling of the Kalevala?

Ilmarinen creates the miraculous sampo (magical device), a "horn of plenty" from which springs an endless bounty of salt, meal, and gold. Ilmarinen, however, is hopelessly in love with the beautiful but arrogant daughter of Mistress Louhi, and uses the sampo to woo her.