(The Four Worlds – source)
The sephirotic tree of life represents a metaphor through which Creation takes place in ten steps and suggests that there are ten emanations involved. There is an alternative version, in which Creation takes place in four steps; this model is called the four worlds. The four worlds can be superposed over the kabbalistic tree and thus the two models became complementary. 
The four worlds are:
- Atziluth – the world of emanations and the divine world of archetypes.
- Briyah – the world of creation or the creating world of archangels.
- Yetzirah – the world of formation or the world of angels and the astral plane.
- Assiah – the active, material world. 
A method through which the four worlds are bound by the sephirotic tree is based on the tradition that each of these contains its own tree; these are sometimes represented by the emanation from Kether to Malkuth.
Another way is dividing the tree in four different regions; here Atziluth corresponds to Kether, Hokhmah, Binah; Briyah corresponds to Chesed, Gevurah and Tiphereth; Yetzirah to Netzah, Hod, Yesod; Assiah to Malkuth. From here we shall have the triangles of the four worlds.
In the case of Atziluth – The celestial triangle starts from a single point, meaning that it comes from the divine unity and divides in two sides. This shows that, although divinity is a unity, any manifestation can be seen in a dual form: masculine and feminine, up and down, in and out, hot and cold etc. One of the duties of a magician is to learn to go through any part in contradiction in order to obtain communion with divinity.
In the case of Briyah – The moral triangle, combination of Strength and Mercy, sustains the evolution of Beauty. If we have too much mercy we become weak and incompetent in fulfilling goals. People use us and we die young. On the other hand, if we show only strength and are totally ruthless we can touch our goals (but never without difficulty), but we won’t have friends and we won’t have real love, thus our success has no sense. Through development of Strength and Mercy, we get a beauty which helps us to attain all goals, and our success has a meaning.
In the case of Yetzirah – The worldly triangle is in connection with successes in the physical realm, not of the mental or spiritual that are found in the moral and celestial triangles. Here, a Victory followed by too much mercy gets to defeat, while the Splendor of a Victory, if is not tempered by Mercy, leads to revolt and ruin. When in balance, there is a Foundation for the successes in this world and a Kingdom that is represented by the only Sephiroth that hangs at the base of the three triangles.
In Atziluth, the archetypal world, everything forms an origin or starts to be something. In that moment, it is simply typified in the largest sense possible: “This was nothing, now it will become life at cellular level”.
In Briyah takes place the creation. This defines the type of Existence in its exact category: “This has been life at cellular level, now it will become a human being.”
In Yetzirah takes place the formation, and the preceding processes are concentrated on finer aspects through clear definition of the result’s nature. “This was cellular life that transformed in human bodies. Now it will structure itself under the form of a small finger-tip belonging to the left hand of a human being.”
In Assiah or material world in which we live, the first three processes are projected from the other worlds under the form of earthly realities. When their purpose has been done, they are reabsorbed by death or dissolved and get back to the stage of nothing before they are given a new origin.
It doesn’t mean that any thing that has an origin must do this complete circle. Something that has an origin can get only to the next level and then get back by that which gave it its origin.
- In Atziluth, which gives the origin is directly seen as an aspect of God.
- In Briyah, the creator is called archangel.
- In Yetzirah, those who give form are
- In Assiah, those that express are called planetary powers.
All is God. It is only a question of which part of God does what.
In Assiah (Physical World), the Tree is planted and cultivated by the senses. Its design is seen with the eye and its colors are appreciated. Wherever we see those colors we should think of the Sephiroth concerned. We can smell the perfumes of the Tree and touch its form attributions. Our ears should be trained to classify sounds and speech appropriately. All this can be worked into ritual practices.
In Yetzirah (Mental World) there is an enormous field of work to be done with the Tree. We can study its philosophy, perceive and solve its problems, consider its pattern-possibilities, and learn one by one the lessons presented to an intelligent pupil by its ordered arrangements. There are no known ends to its mental stimuli or the answers arrived at.
In Briyah (Soul World) the Tree is approached on the ethical and moral level as a code of conduct and standards embodying the highest principles to be found by a seeking soul. Here we learn the laws of living in harmony and balanced relationship with all Being and beings.
In Atziluth (Spirit World) the Tree takes on the aspects of the Living God. Here we approach the Tree with worship, devotion, prayer, and sheer joy of contact with extensions of the Supreme Spirit.
The general notion presented is that God thinks something to become manifest in the material world and – bang! – it simply appears. Creation is a process and every thing must go through the same cyclic laws of life in order to manifest itself in the physical world in which we live in. Kabbalism presents the laws of this process in 4 distinct levels:
- World of Origin – Atziluth. It is the level at which God gives the origin of each thing through the conception of an archetype in its own conscience. From here, every Sephiroth is identified through a name of God. If God gives the sense of function lower than His consciousness, it gives it a lower level of manifestation.
- World of Creation – At this level, the concept is taken further by the orders of spirits called archangels, for they condensate the archetype to be processed by lower orders of spirits.
- World of Formation – Yetzirah. Here the name implies form, structure; all the other detailed specifications are given by the working entities with multiple and different specializations, called angels. Each order of angels is specialized on a single function, but is expert in that function.
- World of Action – Assiah. Here is the place in which the concept manifests in existence as we perceive it. It comes to us through natural laws and through channels of consciousness. The powers at this level are materialized in cosmic phenomenon that we can appreciate through our normal perceptions, such as the stars, planets, zodiacal signs and elemental energies.
That is why the Four Worlds are reduced to the cosmic conscience that concentrates in the material existence through energetic cycles of creation seen from four angles.
At each level, the practicing kabbalist works with different ways of personification of divinity: in Assiah, he works with the elemental spirits, in Yetzirah with angels, in Briyah with archangels and in Atziluth he works directly with each of the ten names of God from each sephiroth. Although the basic idea is that the universe is split into four levels of function, they resonate among themselves.
A practical method of application of the Four Worlds is a business plan seen at a strategic level, a tactical level, an operational level and a functional level. A complete business plan will contain all these four layers by having a simply strategy, but widely spread in tactical methods to reach that goal. Each tactic will be analysed at a level of action and then will be applied in the day to day course of the business.
The worlds must be consistent and balanced between them so that the objective may be reached; each function must be in accordance with the plan (or “that which is above must also be same as below”).
 Notes on Kaballa, Colin Low, p. 197.
 The Middle Pillar, Israel Regardie, p. 46.
 The Ladder of Lights, William G. Gray, p. 16-17.
 The Ladder of Lights, William G. Gray.