Much that was called religion has carried an unconscious attitude of hostility toward life. True religion must teach that life is filled with joys pleasing to the eye of God, that knowledge without action is empty. All men must see that the teaching of religion by rules and rote is largely a hoax. The proper teaching is recognized with ease. You can know it without fail because it awakens within you that sensation which tells you this is something you’ve always known.
– Conclusion of the Commentaries in “Appendix II: The Religion of Dune”

Prophecy and prescience — How can they be put to the test in the face of the unanswered questions? Consider: How much is actual prediction of the “wave form” (as Muad’Dib referred to his vision-image) and how much is the prophet shaping the future to fit the prophecy? What of the harmonics inherent in the act of prophecy? Does the prophet see the future or does he see a line of weakness, a fault or cleavage that he may shatter with words or decisions as a diamond-cutter shatters his gem with a blow of a knife?
– Private Reflections on Muad’Dib by the Princess Irulan

The sequential nature of actual events is not illuminated with lengthy precision by the powers of prescience except under the most extraordinary circumstances. The oracle grasps incidents cut out of the historic chain. Eternity moves. It inflicts itself upon the oracle and the supplicant alike. Let Muad’dib’s subjects doubt his majesty and his oracular visions. Let them deny his powers. Let them never doubt Eternity.

Muad’Dib could indeed see the Future, but you must understand the limits of this power. Think of sight. You have eyes, yet cannot see without light. If you are on the floor of a valley, you cannot see beyond your valley. Just so, Muad’Dib could not always choose to look across the mysterious terrain. He tells us that a single obscure decision of prophecy, perhaps the choice of one word over another, could change the entire aspect of the future. He tells us “The vision of time is broad, but when you pass through it, time becomes a narrow door.” And always, he fought the temptation to choose a clear, safe course, warning “That path leads ever down into stagnation.”
– from Arrakis Awakening by the Princess Irulan

Muad’Dib learned rapidly because his first training was in how to learn. And the first lesson of all was the basic trust that he could learn. It’s shocking to find how many people do not believe they can learn, and how many more believe learning to be difficult. Muad’Dib knew that every experience carries its lesson.

 – from The Humanity of Muad’Dib by the Princess Irulan

I must not fear. Fear is the mind-killer. Fear is the little-death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the fear has gone there will be nothing. Only I will remain.

– Bene Gesserit Litany Against Fear