The liberty tree vs. duration

I saw the Metropolitan Opera's production of John Adams' "Nixon in China" not quite a fortnight ago. Somewhat to my surprise I found it very moving (though less at the finish than at the start), and bought myself a recording of the premiere production from 1987. The work's rhythms and strange haunting melodies have been following me ever since. One moment, from the scene in the aging Chairman Mao's study (Act 1, Scene 2), has not let me be for days, perhaps because we are living its world-historical questions again. It's the first 3 minutes on this clip from 1987:

Here's the libretto by Alice Goodman:

CHOU EN-LAI:
You've said
That there's a certain well-known tree
That grows from nothing in a day,
Lives only as a sapling, dies
Just at its prime, when good men raise
It as their idol.

NIXON:
Not the cross?

MAO:
The Liberty Tree. Let it pass.
It was a riddle, not a test.
The revolution will not last.
It is duration - the regime
Survives in that, and not in time.
While it is young in us it lives;
We can save it, it never saves.

KISSINGER:
And yours will last a thousand years.

(Chou: Sanford Sylvan - Nixon: James Maddalena - Mao: John Duykers)