  Fire turns into water (“sea”), and then half of that quantity turns into earth and half into “fireburst” (prêstêr, a fiery, windy kind of storm phenomenon). The portion that becomes earth turns back into water, in the same quantity it had previously. Here Heraclitus envisages a lawlike transformation of stuff from fire to water to earth; the transformation is reversible, and in it the same relative quantities of stuff are preserved. There is, then, a kind of conservation of matter, or at least overall quantity of matter.  What would make the world to be continuous would be the fact that when one portion of fire turns into water, an equivalent portion of water turns into fire. The overall equilibrium is preserved, even if the water that is now in the sea is not the same water as was in it before. This picture bears a similarity to the image of the river, which remains the same despite its changing material contents. 