skygiants

Actually it's not a Sword in the Stone reference - that's just where most people know it from. The original source for both authors was a famous folk song called The Two Magicians. In this song, a blacksmith tries to court a maiden lady, who in turn refuses him because he is lowly. When he insists that he will win her she changes into a variety of forms to flee from him or hide, while he changes into other forms to pursue - said forms having obvious sexual connotations, this being a folk song.

(Sample lyric:

She turned into a full dress ship and sailed across the sea
But he became a bold captain, and aboard of her went he)