  If B12 is accepted as genuine, it tends to disqualify the other two alleged fragments. The major theoretical connection in the fragment is that between ‘same rivers’ and ‘other waters.’  B12 is, among other things, a statement of the coincidence of opposites. But it specifies the rivers as the same. The statement is, on the surface, paradoxical, but there is no reason to take it as false or contradictory. It makes perfectly good sense: we call a body of water a river precisely because it consists of changing waters; if the waters should cease to flow it would not be a river, but a lake or a dry streambed. There is a sense, then, in which a river is a remarkable kind of existent, one that remains what it is by changing what it contains (cf. Hume Treatise 1.4.6, p. 258 Selby-Bigge). Heraclitus derives a striking insight from an everyday encounter. Further, he supplies, via the ambiguity in the first clause, another reading: on the same people stepping into rivers, other and other waters flow. With this reading it is people who remain the same in contrast to changing waters, as if the encounter with a flowing environment helped to constitute the perceiving subject as the same. (See Kahn 1979.)  B49a, by contrast, contradicts the claim that one can step into the same rivers (and also asserts that claim), and B91[a], like Plato in the Cratylus, denies that one can step in twice. Yet if the rivers remain the same, one surely can step in twice–not into the same waters, to be sure, but into the same rivers. Thus the other alleged fragments are incompatible with the one certifiably genuine fragment.