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

He might at that , Hawat thought. That witch-mother of his is giving him the deep training, certainly. I wonder what her precious school thinks of that? Maybe that's why they sent the old Proctor here—to whip our dear Lady Jessica into line .
Hawat pulled up a chair across from Paul, sat down facing the door. He did it pointedly, leaned back and studied the room. It struck him as an odd place suddenly, a stranger-place with most of its hardware already gone off to Arrakis. A training table remained, and a fencing mirror with its crystal prisms quiescent, the target dummy beside it patched and padded, looking like an ancient foot soldier maimed and battered in the wars.
There stand I , Hawat thought.
"Thufir, what're you thinking?" Paul asked.
Hawat looked at the boy. "I was thinking we'll all be out of here soon and likely never see the place again."
"Does that make you sad?"
"Sad? Nonsense! Parting with friends is a sadness. A place is only a place." He glanced at the charts on the table. " And Arrakis is just another place."
"Did my father send you up to test me?"
Hawat scowled—the boy had such observing ways about him. He nodded. "You're thinking it'd have been nicer if he'd come up himself, but you must know how busy he is. He'll be along later."
"I've been studying about the storms on Arrakis."
"The storms. I see."
"They sound pretty bad."
"That's too cautious a word: bad . Those storms build up across six or seven thousand kilometers of flatlands, feed on anything that can give them a push—coriolis force, other storms, anything that has an ounce of energy in it. They can blow up to seven hundred kilometers an hour, loaded with everything loose that's in their way—sand, dust, everything. They can eat flesh off bones and etch the bones to slivers."
"Why don't they have weather control?"
"Arrakis has special problems, costs are higher, and there'd be maintenance and the like. The Guild wants a dreadful high price for satellite control and your father's House isn't one of the big rich ones, lad. You know that."
"Have you ever seen the Fremen?"
The lad's mind is darting all over today , Hawat thought.
"Like as not I have seen them," he said. "There's little to tell them from the folk of the graben and sink. They all wear those great flowing robes. And they stink to heaven in any closed space. It's from those suits they wear—call them 'stillsuits'—that reclaim the body's own water."
Paul swallowed, suddenly aware of the moisture in his mouth, remembering a dream of thirst. That people could want so for water they had to recycle their body moisture struck him with a feeling of desolation. "Water's precious there," he said.
Hawat nodded, thinking: Perhaps I'm doing it, getting across to him the importance of this planet as an enemy. It's madness to go in there without that caution in our minds .
Paul looked up at the skylight, aware that it had begun to rain. He saw the spreading wetness on the gray meta-glass. "Water," he said.
"You'll learn a great concern for water," Hawat said. "As the Duke's son you'll never want for it, but you'll see the pressures of thirst all around you."
Paul wet his lips with his tongue, thinking back to the day a week ago and the ordeal with the Reverend Mother. She, too, had said something about water starvation.
"You'll learn about the funeral plains," she'd said, "about the wilderness that is empty, the wasteland where nothing lives except the spice and the sandworms. You'll stain your eyepits to reduce the sun glare. Shelter will mean a hollow out of the wind and hidden from view. You'll ride upon your own two feet without 'thopter or groundcar or mount."
And Paul had been caught more by her tone—singsong and wavering—than by her words.
"When you live upon Arrakis," she had said, "khala, the land is empty. The moons will be your friends, the sun your enemy."
Paul had sensed his mother come up beside him away from her post guarding the door. She had looked at the Reverend Mother and asked: "Do you see no hope. Your Reverence?"
"Not for the father." And the old woman had waved Jessica to silence, looked down at Paul. "Grave this on your memory, lad: A world is supported by four things . . ." She held up four big-knuckled fingers. ". . . the learning of the wise, the justice of the great, the prayers of the righteous and the valor of the brave. But all of these are as nothing . . ." She closed her fingers into a fist. ". . . without a ruler who knows the art of ruling. Make that the science of your tradition!"
A week had passed since that day with the Reverend Mother. Her words were only now beginning to come into full register. Now, sitting in the training room with Thufir Hawat, Paul felt a sharp pang of fear. He looked across at the Mentat's puzzled frown.
"Where were you woolgathering that time?" Hawat asked.
"Did you meet the Reverend Mother?"
"That Truthsayer witch from the Imperium?" Hawat's eyes quickened with interest. "I met her."
"She . . ." Paul hesitated, found that he couldn't tell Hawat about the ordeal. The inhibitions went deep.
"Yes? What did she?"
Paul took two deep breaths. "She said a thing." He closed his eyes, calling up the words, and when he spoke his voice unconsciously took on some of the old woman's tone: " 'You, Paul Atreides, descendant of kings, son of a Duke, you must learn to rule. It's something none of your ancestors learned'." Paul opened his eyes, said: "That made me angry and I said my father rules an entire planet. And she said, 'He's losing it.' And I said my father was getting a richer planet. And she said. 'He'll lose that one, too.' And I wanted to run and warn my father, but she said he'd already been warned—by you, by Mother, by many people."
"True enough," Hawat muttered.
"Then why're we going?" Paul demanded.
"Because the Emperor ordered it. And because there's hope in spite of what that witch-spy said. What else spouted from this ancient fountain of wisdom?"
Paul looked down at his right hand clenched into a fist beneath the table. Slowly, he willed the muscles to relax. She put some kind of hold on me , he thought. How?
"She asked me to tell her what it is to rule," Paul said. "And I said that one commands. And she said I had some unlearning to do."