A recurring theme in these myths is the effort of the gods to maintain "maat" against the forces of disorder. They fight vicious battles with the forces of chaos at the start of creation. Ra and Apep, battling each other each night, continue this struggle into the present. Another prominent theme is the gods' death and revival. The clearest instance where a god dies is the myth of Osiris's murder, in which that god is resurrected as ruler of the Duat. The sun god is also said to grow old during his daily journey across the sky, sink into the Duat at night, and emerge as a young child at dawn. In the process he comes into contact with the rejuvenating water of Nun, the primordial chaos. Funerary texts that depict Ra's journey through the Duat also show the corpses of gods who are enlivened along with him. Instead of being changelessly immortal, the gods periodically died and were reborn by repeating the events of creation, thus renewing the whole world. Nonetheless, it was always possible for this cycle to be disrupted and for chaos to return. Some poorly understood Egyptian texts even suggest that this calamity is destined to happen—that the creator god will one day dissolve the order of the world, leaving only himself and Osiris amid the primordial chaos.