Transformation
In short: A motif in which a person, animal or object takes on a different body or material form.
Motif
How does it work in the tale?
In Pygmalion, an ivory statue comes to life, and the touch of a hand reveals the change. In the Frog King, a spell breaks and the prince regains his former shape. One begins a new life and the other restores a lost form.
What do we learn when the frog changes?
In the Grimms’ Frog King, the princess throws the frog against a wall. When he falls, she sees a prince. Only then does the prince himself explain how he came to be enchanted. The transformation changes his appearance and gives the earlier scene at the well a new meaning.