[hielke]

The phrase in the title is also not from Frank Herbert. It is from Lynch's movie adaptation of the books.

[ggm]

...Paul turned back to look at the Emperor, said: ‘When they permitted you to mount your father’s throne, it was only on the assurance that you’d keep the spice flowing. You’ve failed them, Majesty. Do you know the consequences?’ ‘Nobody permitted me to—’ ...

And

... The spice flow, that’s their river, and I have built a dam. But my dam is such that you cannot destroy it without destroying the river. ...’

[simonh]

Sure, but "The spice must flow" specifically as a slogan is an iconic phrase original to the movie.

It would be nice if it could be surreptitiously slipped into the new one somehow, as a tip of the hat to Lynch.

[bbsz]

I've read all of the Herbert's Dune before watching Lynch movie, cited phrase above stood out to me at the time even when embedded within the broader context of a dialogue. Its possible though that I've picked it up from someone who picked it also up from the movie, sure.

[Cthulhu_]

Reminds me of the phrase "Luke, I am your father", which is not actually used in the movie.