43A Censorinus: [There is a <Great> Year whose winter is a great flood (cataclysmos) and whose summer is an ecpyrosis, that is a world conflagration. For it is thought that in these alternating periods the world is now going up in flames, now turning to water. Heraclitus and Linus <believed this cycle to consist of> 10,800 years.] (Cp. Testamonia 13 in Robinson)
43B Simplicius: [Heraclitus posits a certain order (taxis) and fixed time for the change of the cosmos according to some fated necessity (heimarmene anake).] (Cp. D A5)
There is again some debate on the full accuracy of these fragments. Scholars agree that Heraclitus thought that a generation is 30 years. Most scholars agree that Heraclitus, previous to the Stoics, thought that there was a cycle of world creations — a conflagration — with the world ending in fire and re-emerging. Most agree that he thought this occurred each 10,800 years. The cycle of the days of the year (360) multiplied by the number of generations (30) begets an era of creation and destruction (10,800 years).
Heraclitus posits a world ordered by logos. Things occur in the world according to “fated necessity.” It is not a world driven by the gods’ capricious actions but a world driven by what we might characterize as a divine order. The eras are determined.
The Stoic determinism and belief in conflagration are thus foreshadowed by Heraclitus. But this raises the familiar questions of determinism. What becomes of the moral pleas otherwise made (by Heraclitus) if things that occur do so aligned with fated necessity? It would be one person’s fate to make the moral pleas, another’s to ignore them, or not.
Heraclitus’ desire for an objective perspective, his impulse to calculate and rationally examine lead him to an over-confidence in calculation and rationality — or at least an over-confidence that the knowledge exists at present to calculate and explain the world more than it does. He thus commits a fault of so many system builders — of imaginatively stretching beyond what any evidence will support.
Heraclitus appears to be trying to rationally save some of the metaphoric truth of religion and poetry by incorporating the fates, demythologized. The fates give way to rationally “fated necessity.” But in fact, it is the poetic (albeit not religious) truth of what he says, without the detailed calculations, that remains of fundamental value. Worlds go up in flames. They are then reordered. At least our socially constructed worlds do this — here, destruction, rebirth, change continues unabated.
As for what becomes of the physical universe throughout time, as to the details of the patterns of creation and destruction: we are still waiting for knowledge on these questions. We remain immeshed in a reality where poetic metaphor still often reaches where evidence-based reasoning does not.