I'm currently reading House Harkonen and I came upon an interesting point. Spoilers arriving (in case you didn't read the book) There is a point where Warrick (Liet's friend) drinks the water of life and is able to see into the future and I believe it even mentions that he can see where only the Kwisatz Haderach can see. Is this possible considering that the Bene Gesserits can't perform such an act and a simple fremen can?