A single individual cannot exit to the spiritual world. This would be like one individual beginning to develop the whole of physics or chemistry, and then starting to use these sciences. It would be similar to living like a Neanderthal without using all that humanity has achieved thus far, before attaining that knowledge by one’s own resources.
It is for this reason that a beginning student needs a teacher who has already attained the Upper World, and can show the student how to attain each step to develop towards the Upper World. The teacher is a spiritual connection to the student, but the student will understand it only after attaining the Upper World independently.