The nature of each of the levels within the planes of illusions is determined exclusively by the nature of the spirits that reside there. The higher the level, the more evolved the spirit that occupies it, and the more evolved the spiritual environment. The lower the level, the less evolved the spirits who live there, and consequently the pleasant the environment.
Note that I have defined the summerlands in the plane of illusion as parts of Heaven, while the winterlands are not parts of Hell. This is an important distinction. The summerlands are bright and comfortable and are perceived by the residents as happy parts of the spiritual world. Living there is like living in a permanent vacation, each level representing an environment more “luxurious” but less “material” than the one below.
The winterlands are darker and shabbier, but the conditions are still relatively comfortable for the types of spirits that reside there. Winterland spirits would consider their surroundings to be “a step up” from the conditions they experienced while living on earth. Living there would be a bit like an “economy vacation”. However, the souls on lower levels must contend with the behavior of their fellow residents, which is why each descending level of the winterlands is darker and shabbier than the one above.
The thing that most distinguishes the summerlands from the winterlands (and the hells below) is the degree of materiality that the residents create there. The lower the level, the greater the desire of the resident spirits to create earthly props to satisfy their more earthy desires. The higher the level, the more refined the desires of the residents, and they begin to populate their environments with fewer material props and replace them with more and more ethereal and psychological pleasures.
The environments on every plane in the spiritual world, from the deepest hells to the highest celestial Heaven are the communal products of the imaginations of the resident souls that exist on that plane. The nature of those environments depends exclusively on the nature of the spirits themselves. On the lower levels, the spirits tend to create an environment filled with material objects through the power of their imaginations. Myers coined the phrase “Plane Of illusion” because it is in the summerlands and the winterlands that the spirits enjoy the illusion of an extended vacation. The material objects these spirits have created seem real enough to the spirits themselves, but they are only props. The vacation itself is an illusion of heavenly bliss.
It is within the planes of illusion that a soul must make the decision whether to progress up into the higher and more challenging celestial planes, or down, back to the equally challenging materiality of the lower planes, or even back to the earth itself. They have no choice. While the souls on these levels may remain for as long as they like in their respective heavens, they all eventually opt to leave. Eternity is such a long time…And the illusion of luxury gets very boring!
It may seem surprising that any soul would want to descend to a lower level within the spiritual world, but the choice the spirit must make involves the desire for the more material and narcissistic pleasures of a material existence versus an existence based on the more ethereal pleasures of love, wisdom, and altruism. It can be a very difficult decision and it must come from the depths of that soul’s consciousness. Would you really give up all your wealth and possessions to live as an impoverished missionary in an impoverished land?