>(I agree that one could argue that the bank is not part of the river - but no-one did when it appeared above, so I take that as a justification to take it as given.)

I guess, but. we probably can't *know what Heraclitus thought of this point, since all we know of him is from Plato and Aristotle. "You cannot step twice into the same river; for fresh waters are ever pouring upon you." "The sun is new every day." his basic doctrine was that everything is in a state of flux; "nothing ever is, everything is becoming" (Plato), "nothing steadfastly is" (Aristotle).