The Book of Three introduces social concerns that remain central throughout the Prydain Chronicles. Especially significant is the notion of social equality. The greatness of the individual has nothing to do with parents, family, or social class. The protagonist, Taran, a foundling, is a lowly assistant pigkeeper who dreams of becoming a renowned hero. That he indeed eventually becomes king is entirely a matter of his personal qualities, not a result of social standing or education. Like King Arthur, he is raised by a wizard, but unlike Merlin, Dallben does not teach Taran to become a king.

Ecology is also a concern of Alexander.

The threats of the evil Arawn are represented in his abuses of the environment.

In contrast to the destructive god of the underworld, the gentle Medwyn lives in a beautiful, idyllic valley in peace and harmony with nature and animal life.

Medwyn's...