That book-within-a-book, whose false reality actually describes another, more familiar reality, is archetypal of a theme which recurs throughout Dick's writing: the penetration of true reality into a false reality, lifting the shroud of illusion in mysterious ways. With this theme, Dick suggests the questions, who or what is the agent causing this penetration? And why does that agent desire that this reality be known as an artifice? That theme is addressed further in several popular Dick novels, including Ubik, Flow My Tears, The Policeman Said, and Dick's masterwork Valis.
In fast-moving prose, Dick also deals with themes of justice and injustice, gender and power, shame and identity, and the effects of fascism on culture.
An interesting aspect of The Man in the High Castle is that Dick claimed to have written it using the same method that the novelist in the book had used to write his novel, that is, using the I Ching (the Chinese Book of Changes) to decide on plot development.
It is one of Philip Dick's most tightly-structured and character-focused novels and one which deals the least with standard science fiction themes of technological gadgetry.