τὰ πάντα ῥεῖ καὶ οὐδὲν μένει.
Tà pánta rheî kaì oudèn ménei.
"Everything flows, nothing stands still."
Attributed to Heraclitus — Plato, in his dialogue Cratylus, recounts Heraclitus' saying:
τὰ ὄντα ἰέναι τε πάντα καὶ μένειν οὐδέν
Tà ónta iénai te pánta kaì ménein oudèn
"[That] things that exist move and nothing remains still",[23] which he expands:
πάντα χωρεῖ καὶ οὐδὲν μένει καὶ δὶς ἐς τὸν αὐτὸν ποταμὸν οὐκ ἂν ἐμβαίης
Pánta khōreî kaì oudèn ménei kaì dìs es tòn autòn potamòn ouk àn embaíēs
"All things move and nothing remains still, and you cannot step twice into the same stream"
https://en.wikipedia.org/wiki/List_of_Greek_phrases