the two are exactly alike in appearance.  That the spiritual world is such the natural man cannot comprehend, and least of all the sensual man, who believes nothing except what he sees with his bodily eyes and touches with his hands, and therefore takes in by sight and touch.  As his thought is from such things it is material and not spiritual.  Such being the likeness between the spiritual world and the natural world, man can hardly believe after death that he is not in the world where he was born, and from which he has departed.  For this reason death is called simply a translation from one world into another like it. (That the two worlds are thus alike can be seen above, where representatives and appearances in heaven have been treated of, n. 170-176.)

583.  The heavens are in the higher parts of the spiritual world, the world of spirits in the lower parts, and under both are the hells.  The heavens are visible to spirits in the world of spirits only when their interior sight is opened; although they sometimes see them as mists or as bright clouds.  This is because the angels of heaven are in an interior state in respect to intelligence and wisdom; and for this reason they are above the sight of those who are in the world of spirits.  But spirits who dwell in the plains and valleys see one another; and yet when they are separated there, which takes place when they are let into their interiors, the evil spirits do not see the good spirits; but the good spirits can see the evil spirits.  Nevertheless, the good spirits turn themselves away from the evil spirits; and when spirits turn themselves away they become invisible.  But the hells are not seen because they are closed up.  Only the entrances, which are called gates, are seen when they are opened to let in other like spirits.  All the gates to the hells open from the world of spirits, and none of them from heaven.

584.  The hells are everywhere, both under the mountains, hills, and rocks, and under the plains and valleys.  The openings or gates to the hells that are under the mountains, hills, and rocks, appear to the sight like holes and clefts in the rocks, some extended and wide, and some straitened and narrow, and many of them rugged.  They all, when looked into, appear dark and dusky; but the infernal spirits that are in them are in such a luminosity as arises from burning coals.  Their eyes are adapted to the reception of that light, and for the reason that while they lived in the world they were in thick darkness in respect to Divine truths, because of their denying them, and were in a sort of light in respect to falsities because of their affirming them.  In this way did the sight of their eyes become so formed.  And for the same reason the light of heaven is thick darkness to them, and therefore when they go out of their dens they see nothing.  All this makes it abundantly clear that man comes into the light of heaven just to the extent that he acknowledges the Divine, and establishes in himself the things of heaven and the church; and that he comes into the thick darkness of hell just to the extent that he denies the Divine, and establishes in himself what is contrary to the truths of heaven and the church.