The ἐκπύρωσις, or world's conflagration, 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 conflagration 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 conflagration subsides. The paper also deals with the relation between Cleanthes and other early Stoics on the topic of conflagration. In particular, Cleanthes' position seems to differ from Chrysippus'. For in contrast with the Cleanthean god, who causes the conflagration as a side-effect only, the Chrysippean god, according to an influential interpretation put forward by Jaap Mansfeld, causes the conflagration as his ultimate cosmological goal. (shrink)