You never talk of likelihoods on Arrakis. You speak only of possibilities.

Muad'dib rules everywhere," he said.
"Arrakis is not my destination," she insisted.
"Arrakis is the destination of everyone," he said.

Arrakis teaches the attitude of the knife - chopping off what's incomplete and saying: 'Now, it's complete because it's ended here.'

- from "Collected Sayings of Maud'Dib'' by the Princess Irulan

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.

These are illusions of popular history which successful religion must promote: Evil men never prosper; only the brave deserve the fair; honesty is the best policy; actions speak louder than words; virtue always triumpths; a good deed is its own rewards; any bad human can be reformed; religious talismans protect one from demon possession; only females understand the ancient mysteries; the rich are doomed to unhappiness

Look for the possibilities... rather than... locking doors too soon that might in time have opened.