Paul stopped abruptly on a rock shelf, steadied his mother as she stumbled into him.

He was pointing left and she looked along his arm to see that they stood atop a cliff with the desert stretched out like a static ocean some two hundred meters below.

[…]

“Open desert,” she said.

“A wide place to cross,” Paul said.

[…]

“There’s a way to get safely across that open sand,” Paul said. “The Fremen do it. […] If we crossed there making only natural sounds, the kind that don’t attract the worms. . . .”

“It’d have to be sounds without rhythm,” Jessica said.