The Spirits' Book
Book Two - The Spirit World
Chapter VI - Spirit Life
232. Can errant spirits enter all worlds?
“That depends. When a spirit has left the body, it is not fully disengaged from matter. It still belongs to the world in which it has lived, or even a world of the same degree, unless it has risen to a world of a higher degree. This progressive elevation should be the perpetual goal of every spirit, or else it would never reach perfection. A spirit may enter higher worlds, but it would be as an outsider. It can only obtain a glimpse of them, but such glimpses often trigger a desire to improve, to become worthy of the happiness that is enjoyed in those worlds, and to eventually live in them.”