In all religions in which the dead are judged there is a link between earthly justice and the divine justice meted out in the hereafter. Yet the problem of religions, both modern and ancient, is that of the response to the question:
What is the structure of the Other World? How is the hereafter to be imagined in order to display its function to the living Man?
Purgatory is situated in a position that is intermediate on many levels—chronological, functional and symbolic. With respect to time, it falls between the death of the individual and the Judgment to follow, though whether the time of Purgatory is earthly or eschatological has long been a point of division and controversy.
Purgatory finds its functional origins in ancient Judaism. For Jews, gehenna—the valley of Hinnom, in Jerusalem—is not hell. Rather, it is a spiritual forge where the soul is purified for its eventual ascent to gan eiden—the garden of Eden; i.e. heaven. Gehenna is the sinner’s experience in the afterlife, where all imperfections are purged. But more tellingly, it also shares the same geography as gan eiden.
Purgatory is therefore likened to a desert horizon between these two realms: Sky and Earth, heaven and hell. The inferno of the latter coaxes us into the dark heart of Man; the boundless beauty of the former offers us a glimpse of Paradise by comparison. It is the perspective of the individual that makes this Desert one or the other.