"All the water on Arrakis lies beneath its surface in caches. Some are large, some small. Think of a world where there has not been a drop of rain for thousands and thousands of years. Think of the ecology changing to fit that moment after moment, generation after generation. The desert sands are merciless, the storms fierce enough to pick a man clean to the bone, to rend metal from the sky. The only thing that does not fear a sandstorm is Shai-Hulud...and perhaps me, but even I will not walk into one. I am, sadly, flesh and bone. But yes. Water is poison and water is life."

She held out her hand, palm up.

"Let me show you a glimpse of my desert sands. This cave is well enough, but dusk and wormsign? It is a sight."