Fitzgerald and Princesses

Throughout "The Diamond as Big as the Ritz", F. S. Fitzgerald conveys that immorality is caused by self-interest.  Although it is possible to manifest this theme by writing with in-depth rhetoric, it would not be as meaningful as by portraying it through stories, such as fairy tales that, today, everyone is familiar with. 
Fitzgerald's theme is found most prevalent in Disney princess movies.  Once upon a time, Snow White is given a poisoned apple because the Queen wanted to be "the fairest one of all".  The Evil Stepmother locked Cinderella in her room so Cinderella could not marry Prince Charming; the Evil Stepmother wanted to continue to own her, like the stepfather of Moses wanted to continue to own his Hebrew slaves.  Maleficent casts a curse on Aurora as revenge on King Stefan for not inviting her to a celebration for Aurora.  Ursula transforms Ariel into a human for three days, a request as absurd as wanting to witness pink elephants, as part of her evil scheme to become the ruler of the sea.  Mother Gothel kidnaps Rapunzel and channels the magic in Rapunzel's hair to herself continuously in order to look young for eternity.  Mother Gothel's selfishness is evident in the special song that activates Rapunzel's magic hair:  

Flower Gleam and Glow
Let your power shine
Make the clock reverse
Bring Back what once was mine
Heal what has been hurt
Change the Fates' design
Save what has been lost
Bring back what once was mine
What once was mine