"The various worlds are characterized as higher or lower in relation to the degree of their transparency to the divine light, which is their very light and substance.
As one descends in the system of worlds, materiality becomes ever greater: in other words, the beings of the lower worlds feel their independent existence with greater intensity than the beings of the higher; they are more aware of being separate individual selves.
And this consciousness of their separate selfdom blocks the divine plenty and at the same time obscures the truly unchanging essence that lurks beneath the individual personality.
In short, the lower the world, the more it is pervaded by a sense of the “I,” and consequently the more it is subject to the obscuring of the divine essence.
It can be said, however, that all of the worlds--and, indeed any separate realms of being--exists only by virtue of the fact that God makes Himself hidden.
For when the divine plenty is manifested in it complete fullness there is no room for the existence of anything else.
A world can exist only as a result of the concealment of it's Creator.
As one descends from high worlds to lower, with each new level of descent the separateness, the independence of the world from it becomes more pronounced and emphatic, while the divine plenty becomes more hidden.
Hence the creatures in the world of action may reach (as men often do) a condition in which they are not only unaware of the life-giving divine plenty, but may even repudiate its existence altogether.
On the other hand, as on ascends the scale of being, the worlds become ever more clear and transparent to the divine plenty."
--Rabbi Adin Steinsaltz
From "Worlds" in The Thirteen Petalled Rose by Rabbi Adin Steinsaltz