In the remaining Chronicles of Prydain the search of Taran for his true identity continues to be the central theme, but further social concerns and themes are also introduced. In The Castle of Llyr (1966) the theme of power is explored in a variety of ways. The Princess Eilonwy proves her inner strength by destroying the potentially evil book of power although she is well aware that the book would also assure her of sensational achievements unattainable otherwise. In this action she somewhat resembles Galadriel, the elvin queen who in Tolkien's Lord of the Rings favors destruction of the evil ring of power although it will also mean the end of her kingdom on Middle Earth.

Another literary precedent is a similar episode involving Lucy, young heroine of C. S. Lewis's Narnia Chronicles.

Lucy also has an opportunity to use a magic book, but she yields momentarily...