The Fremen religious adaptation, then, is the source of what we now recognize as "The Pillars of the Universe" whose Quizara Tafwid are among us all with signs and proofs and prophecy. They bring us the Arrakeen mystical fusion whose profound beauty is typified by the stirring music built on the old forms, but stamped with the new awakening. Who has not heard and been deeply moved by "The Old Man's Hymn" "?
I drove my feet through a desert
Whose mirage fluttered like a host.
Voraciosu for gloty, greedy for danger,
I roamed the horizons of al-Kulab,
Watching time level mountains
In its search and hunger for me.
And I saw the sparrows swiftly approach,
Bolder than the onrushing wolf.
They spread in the tree of my youth.
I heard the flock in my branches
And was caught on their beaks and claws!"
From "Arrakis Awakening" by the Princess Irulan
A man is crawling across the sands of Dune, alone. At first it sounds like he might be one of the Fremen, with his blue on blue eyes - but it turns out that he is Liet-Kynes, the Imperial Planetologist. (Who actually thinks of himself as both ecologist AND Fremen)
He knows that the sand will soon explode into a huge Spice blow, and that he is in mortal danger if he cannot get away.
The Harkonnen have left him out in the desert without water or a stillsuit - so that he will be killed by the very planet for which he is an Imperial stewart.
He is delerious from the heat - probably dying. He keeps hearing his father's voice. Telling him basic ecological facts he has known since he was a child. However, we the readers do not know Imperial planetology science, so it helps us understand his work - both for the planet and among the Fremen - much better.
And the hawks - symbols of the Atreides - circle over him. Fitting, as he has been sentenced to death for helping Paul and Jessica.
We learn that Liet and his father have been working with the Fremen to make Dune into a planet filled with life. First to make grasslands, then scrubby forests. And working forth from there...
We learn that to Liet's father the very worst thing that could ever happen to the Fremen was to fall into the Hands of a Hero - and we learn that Liet has possibly just put them into such hands by passing word to the Fremen to take in Paul Atreides.
And then the planet that he loves kills Liet in a spice blow. His last thought is that the most persistent principles in the universe are accident and error.