The εκπυ´ρωσιζ, or world's con flagration, followed by the restoration of an identical world seems to go against the rationality of the Stoic god. The aim of this paper is to show that Cleanthes, the second head of the School, can avoid this paradox. According to Cleanthes, the con flagration is an inevitable side-effect of the necessary means used by god to sustain the world. Given that this side-effect is contrary to god's sustaining activity, but unavoidable, god's rationality requires the restoration of an identical world once the con flagration subsides. The paper also deals with the relation between Cleanthes and other early Stoics on the topic of con flagration. In particular, Cleanthes' position seems to diff er from Chrysippus'. For in contrast with the Cleanthean god, who causes the con flagration as a side-effect only, the Chrysippean god, according to an in fluential interpretation put forward by Jaap Mansfeld, causes the con flagration as his ultimate cosmological goal.