The philosophy of Heraclitus is summed up in his cryptic utterance:
ποταμοῖσι τοῖσιν αὐτοῖσιν ἐμϐαίνουσιν, ἕτερα καὶ ἕτερα ὕδατα ἐπιρρεῖ.
Potamoisi toisin autoisin embainousin, hetera kai hetera hudata epirrei
"Ever-newer waters flow on those who step into the same rivers ."
The quote from Heraclitus appears in Plato's Cratylus twice; in 401,d as:
τὰ ὄντα ἰέναι τε πάντα καὶ μένειν οὐδέν"
Ta onta ienai te panta kai menein ouden
"All entities move and nothing remains still"
and in 402,a
"πάντα χωρεῖ καὶ οὐδὲν μένει" καὶ "δὶς ἐς τὸν αὐτὸν ποταμὸν οὐκ ἂν ἐμβαίης"
Panta chōrei kai ouden menei kai dis es ton auton potamon ouk an embaies
"Everything changes and nothing remains still ... and ... you cannot step twice into the same stream"
Instead of "flow" Plato uses chōrei, to change chōros.
The assertions of flow are coupled in many fragments with the enigmatic river image:
Ποταμοῖς τοῖς αὐτοῖς ἐμβαίνομέν τε καὶ οὐκ ἐμβαίνομεν, εἶμέν τε καὶ οὐκ εἶμεν.
"We both step and do not step in the same rivers. We are and are not."