In a development of a cosmogonical view already alluded to in the "Vendidad" (21.15), "aban" is the essence of a "great gathering place of the waters" (Avestan: "Vourukasha", middle Persian: "Varkash") upon which the world ultimately rested. The great sea was fed by a mighty river (proto-Indo-Iranian: "*harahvati", Avestan: "Aredvi Sura", middle Persian: "Ardvisur"). Two rivers, one to the east and one to the west, flowed out of it and encircled the earth ("Bundahishn" 11.100.2, 28.8) where they were then cleansed by "Puitika" (Avestan, middle Persian: "Putik"), the tidal sea, before flowing back into the "Vourukasha".