In Dante's Divine Comedy, each version of the afterlife contains nine different "levels" - the nine "circles of hell" in the Inferno, the two levels of ante-Purgatory and the seven terraces in Purgatorio, and the nine concentric spheres in Paradiso.  Each of the nine is then joined by a tenth and final level, the greatest level.  Satan is the tenth level of hell, the Garden of Eden the tenth of purgatory and God Himself the tenth of heaven.  Across each version of the afterlife is the theme of 9 + 1 = 10.