The number seven pops up everywhere in esoteric sciences.
In addition to Vianna Stiebal's teaching what the 7 planes are, here is an even more esoteric interpretation:
The 7 Planes of Existence
Just as there are seven colors in the rainbow and seven tones in a musical scale, each with a different vibratory rate, there are seven levels of being on the spectrum of creation. The slowest speed of vibration occurs on the physical plane; the highest, on the buddhaic plane. From the buddhaic plane, energy returns to its source, the Tao.
- Physical plane: The densest of the seven planes; where we presently reside.
- Astral plane: The second plane of creation. Its medium is concrete emotional energy. It is where our consciousness is focused between lifetimes and when we're finished with the physical plane.
- Causal plane: The third plane of creation. Its medium is concrete intellectual energy. It is Michael's plane of existence.
- Akashic plane: The central, neutral plane of creation that interconnects the other six. The distilled knowledge of the universe is recorded there. This is the records generated of everything that happens in the universe as it occurs. The appearance is that all matter and energy have a sort of built-in digital recording device, storing its entire history in a photographic code, but the records are actually windows into the past. The records show events exactly as they were experienced, so the information in them begins raw-it is not clarified, understood, and assimilated until a consciousness takes responsibility for doing so. Once it is fully assimilated, it is stored on the akashic plane
- Mental plane: The fifth plane of creation. Its medium is abstract intellectual energy, emphasizing truth. The infinite soul who incarnated as Lao-tzu taught from this plane.
- Messianic plane: The sixth plane of creation. Its medium is abstract emotional energy, emphasizing love. The infinite soul who incarnated as Jesus taught from this plane.
- Buddhaic plane: The highest plane of creation. Its medium is pure or abstract kinetic energy. We experience the buddhaic plane just before fully refocusing our awareness in the Tao. The infinite soul who incarnated as Buddha taught from this plane.
There are etheric, nonsolid levels of the physical plane both lower and higher in frequency than our physical bodies. Some people with psychic skills can see them. The fact that they can be physically seen indicates that they are part of the physical plane. We cannot physically see what is nonphysical, although we may translate our nonphysical perceptions into physical images.
The etheric substance lower in vibration than the solid physical connects it with the Tao. This is the realm of devas, or nature spirits; it could be called the “lower physical plane.” The etheric substance higher in vibration than the solid physical connects it with the astral; it is in the realm of what could be called the “upper physical plane.”
It is the domain of “ghosts,” and some extraterrestrials. The ethereal life form of the “higher sentients” who lived on earth before the “fall of man” was also of the upper physical plane. What we consider solid substance, as well as other vibrations that we can directly perceive such as light and sound, exist in the “middle physical plane.”