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

Someone signaling!
She tried to read the message, but it was in no code she had ever learned.
Other lights had come on down on the plain beneath the cliffs: little yellows spaced out against blue darkness. And one light off to their left grew brighter, began to wink back at the cliff—very fast: blinksquirt, glimmer, blink!
And it was gone.
The false star in the cliff winked out immediately.
Signals . . . and they filled her with premonition.
Why were lights used to signal across the basin? she asked herself. Why couldn't they use the communications network?
The answer was obvious: the communinet was certain to be tapped now by agents of the Duke Leto. Light signals could only mean that messages were being sent between his enemies—between Harkonnen agents.
There came a tapping at the door behind them and the voice of Hawat's man; "All clear, sir . . . m'Lady. Time to be getting the young master to his father."
It is said that the Duke Leto blinded himself to the perils of Arrakis, that he walked heedlessly into the pit. Would it not be more likely to suggest he had lived so long in the presence of extreme danger he misjudged a change in its intensity? Or is it possible he deliberately sacrificed himself that his son might find a better life? All evidence indicates the Duke was a man not easily hoodwinked.
—from "Muad'Dib: Family Commentaries" by the Princess Irulan
The Duke Leto Atreides leaned against a parapet of the landing control tower outside Arrakeen. The night's first moon, an oblate silver coin, hung well above the southern horizon. Beneath it, the jagged cliffs of the Shield Wall shone like parched icing through a dust haze. To his left, the lights of Arrakeen glowed in the haze—yellow . . . white . . . blue.
He thought of the notices posted now above his signature all through the populous places of the planet: "Our Sublime Padishah Emperor has charged me to take possession of this planet and end all dispute."
The ritualistic formality of it touched him with a feeling of loneliness. Who was fooled by that fatuous legalism? Not the Fremen, certainly. Nor the Houses Minor who controlled the interior trade of Arrakis . . . and were Harkonnen creatures almost to a man .
They have tried to take the life of my son!
The rage was difficult to suppress.
He saw lights of a moving vehicle coming toward the landing field from Arrakeen. He hoped it was the guard and troop carrier bringing Paul. The delay was galling even though he knew it was prompted by caution on the part of Hawat's lieutenant.
They have tried to take the life of my son!
He shook his head to drive out the angry thoughts, glanced back at the field where five of his own frigates were posted around the rim like monolithic sentries.
Better a cautious delay than . . .
The lieutenant was a good one, he reminded himself. A man marked for advancement, completely loyal.
"Our Sublime Padishah Emperor . . . "
If the people of this decadent garrison city could only see the Emperor's private note to his "Noble Duke"—the disdainful allusions to veiled men and women: "—but what else is one to expect of barbarians whose dearest dream is to live outside the ordered security of the faufreluches?"
The Duke felt in this moment that his own dearest dream was to end all class distinctions and never again think of deadly order. He looked up and out of the dust at the unwinking stars, thought: Around one of those little lights circles Caladan . . . but I'll never again see my home . The longing for Caladan was a sudden pain in his breast. He felt that it did not come from within himself, but that it reached out to him from Caladan. He could not bring himself to call this dry wasteland of Arrakis his home, and he doubted he ever would.
I must mask my feelings , he thought. For the boy's sake. If ever he's to have a home, this must be it. I may think of Arrakis as a hell I've reached before death, but he must find here that which will inspire him. There must be something .
A wave of self-pity, immediately despised and rejected, swept through him, and for some reason he found himself recalling two lines from a poem Gurney Halleck often repeated—
"My lungs taste the air of Time
Blown past falling sands . . . "
Well, Gurney would find plenty of falling sands here, the Duke thought. The central wastelands beyond those moon-frosted cliffs were desert—barren rock, dunes, and blowing dust, an uncharted dry wilderness with here and there along its rim and perhaps scattered through it, knots of Fremen. If anything could buy a future for the Atreides line, the Fremen just might do it.
Provided the Harkonnens hadn't managed to infect even the Fremen with their poisonous schemes.