Marina Warner's novel, Indigo is inspired by Shakespeare's The Tempest. Carefree Xanthe is a descendant of colonists who holds her ancestry lightly until she lies dying on the ocean bed. And this is the moment that she writes her letter to Xaphania, the leader of the rebel angels, who first appears in The Amber Spyglass by Philip Pullman.

 

Xaphania's currency is not the blue water of the Caribbean ocean, but dust. This for her, is where the power lies. So Xanthe writes to Xaphania in blue ink from her blue death bed, "there is no dust in my throat but water."