Consider a river:
What an enigma,
Forever flowing forward
From time immemorial
Carrying enough water
In that time
To drain all the oceans.

And the water always moving
But the white patches
Staying stationary
Except for some perturbations.

It is as though the water
is flowing through a tube
Of gravity's construction.

Of course we now know
A river's counterflow
Is in the sky,
A barge train of cloud carries
All a river's water upstream
And dumps it down the watershed.