In Norse mythology Mjolnir is the hammer of Thor. In the 13th century it was written: "He [Thor] would be able to strike as firmly as he wanted, whatever his aim, and the hammer would never fail, and if he threw it at something, it would never miss and never fly so far from his hand that it would not find its way back, and when he wanted, it would be so small that it could be carried inside his tunic."
