What are the Spiritual Worlds?
The wisdom of Kabbalah explains, that initially a single desire to receive was created, which as a result of the influence of the creating pure, bestowing force, evolved through four stages, until a raw desire is formed, which senses its total opposition to its source.
As a result of this unpleasant sensation of total opposition the desire restricts itself then builds a “self-control” structure, with a Rosh (head), with a single purpose, to direct its future development in a way of achieving full similarity with the source.
As soon add this “self-control” structure, called “the Partzuf,” is born, the system of “Creation,” begins to sort out the “unemployed” (non-similar, unable to bestow) desires on its waiting list, placing the weakest, easiest to handle desires at the top of the list, and the most intense, unruly ones at the bottom. Creation divides these desires into four categories, similar to the four stages in the evolution of desires. It refers to each category as an Olam (world), from the Hebrew word Haalama (concealment), since these desires must be kept separated and concealed from the lights until they can be operated correctly—with the aim to bestow. Thus, the desires with qualities most similar to Stage One are called “the world of Atzilut,” those most similar to Stage Two form “the world of Beria,” with those most similar to Stage Three forming “the world of Yetzira,” and those most similar to Stage Four becoming “the world of Assiya” (see diagram). For short, they are called “ABYA.”
When Kabbalists describe the spiritual realm—where desires work with the aim to bestow—they usually divide it into worlds and describe what happens in them (how desires actually receive). Therefore, they often refer to everything that precedes the worlds of ABYA as a world as well, and call it “the world of AK” (Adam Kadmon—the primordial man). In a way, the world of AK parallels the Root Stage, or Stage Zero, in the evolution of desires.
Note that our world is not mentioned among the spiritual worlds. Because our world is based on egoism, and the worlds in Kabbalah reflect levels of bestowal, our world is not considered part of the spiritual (with the aim to bestow) system.