On the eve of departure from Caladan, Duke Leto enters the training room where Paul is studying. Leto is exhausted but determined not to show it, knowing that Arrakis will allow little rest. Paul, troubled by the Reverend Mother’s warning that there is “nothing” for his father, asks whether Arrakis is as dangerous as everyone says.

Leto admits the danger and explains that Arrakis is more than a trap: it is also an avenue into CHOAM power through spice control. Because melange is unique, cannot be manufactured, and underwrites immense profits across the Great Houses, any reduction in spice production would turn the Landsraad against the Atreides. Leto reveals that the Harkonnens have stockpiled spice for years and intend the Atreides to be blamed for a production failure.

Paul presses Leto on why House Atreides would knowingly enter the trap. Leto explains that recognizing the trap is the first step toward escaping it, and that stockpiling reveals enemies, including the Padishah Emperor. Leto expects the Emperor’s Sardaukar to be used secretly in Harkonnen disguise, because open violation of the Great Convention would be too blatant.

Leto then reveals the strategic value of the Fremen. Comparing Arrakis to the Emperor’s hellish prison planet Salusa Secundus, Leto suggests harsh environments can produce elite warriors like the Sardaukar. Since the Harkonnens have underestimated and abused the Fremen, Leto hopes to ally with them; Duncan Idaho has already been sent to negotiate and to let the Fremen judge the Atreides through him.

The conversation shifts to practical matters: Gurney’s report on Paul’s weapons training, the coming journey aboard a Guild Heighliner, and the Guild’s secretive monopoly. Finally, Leto tells Paul that Jessica wanted him to reveal a major truth: Paul has been trained as a potential Mentat. Paul immediately understands the hidden pattern behind Hawat and Jessica’s lessons and chooses to continue the training, while his renewed sense of “terrible purpose” remains unresolved.