Full Idea
It isn't even reasonable to say that there is such a thing as knowledge, Cratylus, if all things are passing on and none remain.
Gist of Idea
There can't be any knowledge if things are constantly changing
Source
Plato (Cratylus [c.375 BCE], 440a)
Book Reference
Plato: 'Complete Works', ed/tr. Cooper,John M. [Hackett 1997], p.155
A Reaction
This encapsulates Plato's horror at Heraclitus scepticism about the stable identity of things. It leads to the essentialism of Aristotle and Leibniz, who fear that there is no knowledge if we can't pin down individual identities. Know processes?