What are the motifs in Heretics of Dune by Frank Herbert?

Technology is a recurring idea in the novel. Technology reaches a low-point in the previous novel, God Emperor of Dune, where the Tyrant Leto II forces humanity back to primitive conditions and restricts travel, in order to minimize causes of warfare. Leto II uses Ixian and Bene Tleilaxu technology, marginally legal since the time of the Butlerian Jihad, which outlaws anything that artificially simulates human thought and the use of atomic weapons, but allows the outlawed technology to no one else.