Eventually, the soul moves to the next level of the ethereal plane where it prepares for the next steps of spiritual evolution. Upon this plane, a soul can decide if it wants to return now to a new incarnation, or if it would rather perform spiritual service on this plane of existence for a brief time. You can think of this plane as the Land of Spiritual Guardians. Those spiritual beings who work with those in physical incarnations as personal spiritual guides, or teachers.
The last realm of the pagan ethereal world is the plane of divine energies. When a soul has reached it's pinnacle of spiritual evolution where it no longer needs to return to the physical world, it has the option of moving to the divine plane of existence.