Everything flows and nothing stays.
Everything flows and nothing abides.
Everything gives way and nothing stays fixed.
Everything flows; nothing remains.
All is flux, nothing is stationary.
All is flux, nothing stays still.
All flows, nothing stays.
~ Heraclitus of Ephesus
Oh, gosh, so true!
Ah the Stoics:) (see here for more: https://en.wikipedia.org/wiki/Heraclitus#Stoics)
Then the fluid nature of everything is constant, and absolutely so.