The Chronicles of Narnia she felt were upsetting to children. Poskanzer also noted Lewis presented his Christian message subtly enough as to avoid boring children with overt sermonizing. Examples include: Philip Pullman's fantasy series, "His Dark Materials", is seen as a response to "The Chronicles". Pullman is a self-described atheist who wholly rejects the spiritual themes that permeate "The Chronicles", yet his series nonetheless addresses many of the same issues and introduces some similar character types, including talking animals. In another parallel, the first books in each series – Pullman's "Northern Lights" and "The Lion, the Witch, and the Wardrobe" – both open with
The Chronicles of Narnia book: Lewis's interest in the literary symbolism of medieval and Renaissance astrology is more overtly referenced in other works such as his study of medieval cosmology "The Discarded Image", and in his early poetry as well as in "Space Trilogy". Narnia scholar Paul F. Ford finds Ward's assertion that Lewis intended "The Chronicles" to be an embodiment of medieval astrology implausible, though Ford addresses an earlier (2003) version of Ward's thesis (also called "Planet Narnia", published in the "Times Literary Supplement"). Ford argues that Lewis did not start with a coherent plan for the books, but Ward's book answers this