In Norse mythology , the goddess Iðunn is portrayed in the Prose Edda ( written in the 13th century by Snorri Sturluson ) as providing apples to the gods that give them eternal youthfulness .
In Norse mythology , the goddess Iðunn gives apples to the gods in Prose Edda ( written in the 13th century by Snorri Sturluson ) that makes them young forever .