Invisibility has a long literary history, from science fiction, like in H.G. Wells’s Invisible Man, to fantasy, like in J.R.R. Tolkien’s Lord of the Rings. Often, the difference is between methodology and motive. Wells focused on scientific accuracy to illustrate “the messy outcome of this collision between science and myth.” Tolkien employs invisibility as metaphor; the magic behind it is unimportant. Philip Ball explains further in the Guardian:

Fairytale invisibility is often an agency of seduction and voyeurism (see the Grimms’ The Twelve Dancing Princesses), or a gateway to Faerie and other liminal realms. It’s precisely because children don’t ask “How is that possible?” that we shouldn’t fret about filling their heads with such allegedly irrational ideas.