I like to think about the first book of the Dune saga as a trial to open the mind, to look beyond and use your capabilities far from your self-imposed limits, more like the Spice Agony for the initiated, and later on you will never be able to see the world the same way, so the story got a hold on you that much and you start to use your wits like a Mentat or a Bene Gesserit, and see what the writer wanted you to see, plans within plans within plans... the rest of the saga runs assuming you have that potential and you are able to see even the slightest detail in the plot. Frank Herbert really knew how to involve and motivate the reader to THINK. Leto II said sonethink about it... he hated people incapable of think