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.