In particular, the kind of thing that is destroyed when you grind it down into powder.

Humans need fantasy to be human.

"Tooth fairies? Hogfathers? Little—"

Yes. As practice. You have to start out learning to believe the little lies.

"So we can believe the big ones?"

Yes. Cars. Chairs. Bicycles. That sort of thing.

"They're not the same at all!"

You think so? Then take the universe and grind it down to the finest powder and sieve it through the finest sieve and then show me one atom of car, one molecule of bicycle.

Susan and Death, in Hogfather by Terry Pratchett

Same thing.