From "Manual of Muad'Dib" by the Princess Irulan

I am steward of this sand , he thought.
He realized that he was semi-delirious, that he should dig himself into the sand, find the relatively cool underlayer and cover himself with it. But he could still smell the rank, semisweet esters of a pre-spice pocket somewhere underneath this sand. He knew the peril within this fact more certainly than any other Fremen. If he could smell the pre-spice mass, that meant the gasses deep under the sand were nearing explosive pressure. He had to get away from here.
His hands made weak scrabbling motions along the dune face.
A thought spread across his mind—clear, distinct: The real wealth of a planet is in its landscape, how we take part in that basic source of civilization—agriculture .
And he thought how strange it was that the mind, long fixed on a single track, could not get off that track. The Harkonnen troopers had left him here without water or stillsuit, thinking a worm would get him if the desert didn't. They had thought it amusing to leave him alive to die by inches at the impersonal hands of his planet.
The Harkonnens always did find it difficult to kill Fremen , he thought. We don't die easily. I should be dead now . . . I will be dead soon . . . but I can't stop being an ecologist .
"The highest function of ecology is understanding consequences."
The voice shocked him because he recognized it and knew the owner of it was dead. It was the voice of his father who had been planetologist here before him—his father long dead, killed in the cave-in at Plaster Basin .
"Got yourself into quite a fix here, Son," his father said. "You should've known the consequences of trying to help the child of that Duke."
I'm delirious , Kynes thought.
The voice seemed to come from his right. Kynes scraped his face through sand, turning to look in that direction—nothing except a curving stretch of dune dancing with heat devils in the full glare of the sun.
"The more life there is within a system, the more niches there are for life," his father said. And the voice came now from his left, from behind him.
Why does he keep moving around? Kynes asked himself. Doesn't he want me to see him?
"Life improves the capacity of the environment to sustain life," his father said. "Life makes needed nutrients more readily available. It binds more energy into the system through the tremendous chemical interplay from organism to organism."
Why does he keep harping on the same subject? Kynes asked himself. I knew that before I was ten .
Desert hawks, carrion-eaters in this land as were most wild creatures, began to circle over him. Kynes saw a shadow pass near his hand, forced his head farther around to look upward. The birds were a blurred patch on silver-blue sky—distant flecks of soot floating above him.
"We are generalists," his father said. "You can't draw neat lines around planet-wide problems. Planetology is a cut-and-fit science."
What's he trying to tell me? Kynes wondered. Is there some consequence I failed to see?
His cheek slumped back against the hot sand, and he smelled the burned rock odor beneath the pre-spice gasses. From some corner of logic in his mind, a thought formed: Those are carrion-eater birds over me. Perhaps some of my Fremen will see them and come to investigate .
"To the working planetologist, his most important tool is human beings," his father said. "You must cultivate ecological, literacy among the people. That's why I've created this entirely new form of ecological notation."
He's repeating things he said to me when I was a child , Kynes thought.
He began to feel cool, but that corner of logic in his mind told him: The sun is overhead. You have no stillsuit and you're hot; the sun is burning the moisture out of your body .
His fingers clawed feebly at the sand.
They couldn't even leave me a stillsuit!
"The presence of moisture in the air helps prevent too-rapid evaporation from living bodies," his father said.