  In fact, Marcovich (1967) has succeeded in showing how a misreading of B12 could lead to an interpretation such as that embodied in A6 and B91[a]. It is possible to see Cratylus, a late follower of Heraclitus, supplying the wayward reading, and then adding his famous rejoinder that one cannot step into the same river even once (although the reading may go back earlier to Hippias:  Mansfeld 1990: 43–55). Since Plato is alleged to have heard Cratylus’ lectures, he may well have derived his reading from Cratylus’ criticism. 