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

I am a sandrider , Paul told himself.
He glanced down at the hooks in his left hand, thinking that he had only to shift those hooks down the curve of a maker's immense side to make the creature roll and turn, guiding it where he willed. He had seen it done. He had been helped up the side of a worm for a short ride in training. The captive worm could be ridden until it lay exhausted and quiescent upon the desert surface and a new maker must be summoned.
Once he was past this test, Paul knew, he was qualified to make the twenty-thumper journey into the southland—to rest and restore himself—into the south where the women and the families had been hidden from the pogrom among the new palmaries and sietch warrens.
He lifted his head and looked to the south, reminding himself that the maker summoned wild from the erg was an unknown quantity, and the one who summoned it was equally unknown to this test.
"You must gauge the approaching maker carefully," Stilgar had explained. "You must stand close enough that you can mount it as it passes, yet not so close that it engulfs you."
With abrupt decision, Paul released the thumper's latch. The clapper began revolving and the summons drummed through the sand, a measured "lump . . . lump . . . lump . . . "
He straightened, scanning the horizon, remembering Stilgar's words: "Judge the line of approach carefully. Remember, a worm seldom makes an unseen approach to a thumper. Listen all the same. You may often hear it before you see it."
And Chani's words of caution, whispered at night when her fear for him overcame her, filled his mind: "When you take your stand along the maker's path, you must remain utterly still. You must think like a patch of sand. Hide beneath your cloak and become a little dune in your very essence."
Slowly, he scanned the horizon, listening, watching for the signs he had been taught.
It came from the southeast, a distant hissing, a sand-whisper. Presently he saw the faraway outline of the creature's track against the dawnlight and realized he had never before seen a maker this large, never heard of one this size. It appeared to be more than half a league long, and the rise of the sandwave at its cresting head was like the approach of a mountain.
This is nothing I have seen by vision or in life , Paul cautioned himself. He hurried across the path of the thing to take his stand, caught up entirely by the rushing needs of this moment.
"Control the coinage and the courts —let the rabble have the rest." Thus the Padishah Emperor advises you. And he tells you: "If you want profits, you must rule." There is truth in these words, but I ask myself: "Who are the rabble and who are the ruled?"
—Muad'Dib's Secret Message to the Landsraad from