The realization of his true nature as a timeless awareness comes to Leto as he traverses the desert dunes under a sky controlled by Ixian satellites. He reflects on how the Ixians had incorrectly anticipated a hydraulic despotism, while he maintains subtle controls over the environment. Siona follows him closely, having read the stolen journals and received ominous preparations from her father Moneo. Moneo had warned her that the worm would come and that she must find a way to live in his presence. When Leto descends in his cart, he leads Siona away from the tower, offering her a path through the rocky basement complex and onto the sands of the Sareer.
Standing atop a high dune, Siona takes in the vast, flat horizon where all familiar reference points vanish, leaving her isolated in a dangerous space. When she abruptly asks if Leto has a personal religion, he answers with an ancient phrase meaning nature makes no leaps, which he translates to prod her ancient memories. He invites her to climb onto his back, and she complies, experiencing firsthand the sensation of riding a giant sandworm across the dunes. Leto steels himself against pity, reminding himself that even if she dies, it would be a required event, though his test is designed to sensitize her to her future and the Golden Path.
As they travel deeper into the braided dunes of the central erg, Leto speaks of their Fremen past and the origins of their traditions, noting that Siona's fears are building. He stops to ask her if they have left any tracks, leading her to realize that the wind has covered their path and that she cannot simply run back to the Little Citadel. He reveals that they have travelled about sixty kilometres and tells her to eat a dried protomor cube from her stillsuit pouch while he explains that she must find faith in herself. Siona questions if she is truly free to leave, but Leto points out the dangers of the steep dunes and the reality of the desert.
Recognizing her own inability to survive the harsh wilderness alone, Siona confronts Leto about whether she had a choice in being brought here. He defends his actions by noting the difficult nature of being born an Atreides, reminding her that he knows this burden well. Rather than continuing their journey immediately, Leto stops in the shadow of a dune, announcing that they will wait out the day there because it uses less water to travel by night.