Ancient Egypt had more than one heaven, and most of their heavens were subdivided into sections or parts akin to, and probably best equated with the astral plane.
As the astral plane has many different levels, the lowest next to the earthly plane, and highest sections up to and pass most of earth’s religions concept of heaven, the astral plane is like a onion with the material world in the center, and the layers going outward (or inward, Or higher, or whatever). As most religions heavens are manifested in the astral plane, they are also separate from each other.
This is also true in Egyptian heavens of the astral plane. The Book of the Dead (a misnomer as the Egyptians never called it that), lists the sections of the Heaven of Osiris. As you read the book, you also see that there is a specific way to get to the heaven and through it.
There is an ancient Egyptian writing from a scribe that says, in effect: “If you don’t use the specific directions to get to a particular heaven, you won’t get there but to a false heaven.”
As most of us are aware, the astral plane is composed and made up of the thoughtforms of mankind and of the gods, hence, there is an Egyptian heaven that was formed by the thousands of people who have conceptualized it since the beginning of the 1800’s, made stronger through the Rosecrucians and Blavatsky’s, and into the modern metaphysical movement. But it is NOT the ancient Egyptian heaven. Hence, you can’t simply just astrally project in order to get to a real Egyptian heaven.
You have to follow the directions by the ancient Egyptians in order to make it to one of their specific heavens.
You may even have to change your astral form to conform to a certain type in order to enter. For example, one of the ways to get to the Horus heaven is to have project to the Nile, and do certain things in order for a boat with a hawk on it to come over to the bank and pick you up to take you to the Horus Heaven.
One of the things you have to do, and not the only thing, in order to get into the Heaven of Isis is to change your astral body into the shape of a bird, a Swallow!
So if someone, no matter how much you respect them, tells you that they dreamed or astrally projected to astral Egypt, they are wrong, unless they know the specific ways to do it. The Egyptians then, have a sort of astral lock on the proverbial doors to the entrance of their heavens, and you can’t just blindingly end up there without the right keys to get there. I can probably safely say that no more than a couple of dozen people in the last century have been able to enter these heavens, and no one who has written a book about Egyptian metaphysics has (including Eliz. Hatch who wrote Initiation; who knows nothing about Ptahhotep).
The teachers are still pretty much in the Egyptian heavens, waiting to teach the student who is able to get there.
Although the ancient Egyptians had the wherewithal to go into drug induced states (they had mandrake and poppies for medicine), I have yet to find one example of them using them for magic or astral projection.
Astral sight was taught before astral projection, using techniques that we still use today.
Several techniques that are used today in astral projection today were also used in astral projection then, but usually, a priest led the student in the first several experiences in order for the student to get used to the experience and feelings associated with projection to a particular heaven.
Therefore the guided trips were first used. Usually the first trips were done in the temples (easier to do with all of the power already resident in the temples). Some, like the priests of Horus were also done by the Nile’s edge, the student going into a sleep, the priest astrally projecting and drawing the students astral body and consciousness out doing what is necessary for the Horus boat to arrive on the astral Nile, then going on the trip through the Horus heaven. Sometimes it was done out in the desert. …
When a teacher died, such as Imhotep, he went to the appropriate heaven and taught from there (according to the ancient Egyptians, who said that at that point their teachers on earth would astrally project to the heaven to be taught by him). At that point, all priest/esses called him Master, or another appropriate remark. Since apparently there was much connections between the two worlds, the priest/esses knew when Imhotep finally left the astral heaven to ascend beyond and into the world of the god/desses. At that point Imhotep on earth was called a God (this process is found in a papyrus fragment translated courtesy of the French Institute of Archeology of Cairo).
Hence, if you know when Imhotep or some other lived, and know that after death he was called a master, then the earliest time that he, or she, started being called a God was the time he moved out of the astral plane.
Some other traditions use the symbology of ladders as an analogy of the ascent to their astral plane. Each rung represents a god or goddess to invoke, the ladder is always held by two gods, which symbolize the type of path being used. In some other traditions, there was a way to ascend through the astral plane and into the spiritual realm, reserved for the higher priests who have passed the Guardian of the Threshold. These traditions can be found when you go to Egypt for in some of the temples the staircase to the roof will have a god/dess for each step, symbolizing those that you will need to ascend to the spiritual plane. …
Following the Eastern Tradition of the astral plane, the Egyptians have an almost exact duplicate of the concept. Basically it says that there is a plane of existence between the realm of the high gods and earth, called the astral plane, which has layers like an onion. The astral plane is made up of the mind stuff of heaven and earth dwellers alike and is as real as both. To the Eastern people, all the heavens of all the religions are there. To both Egyptian and Easterners, to get there you astrally project or out of body experience. Although the Egyptians had a more elaborate version.
The Egyptians, therefore, which had several religious traditions, of which Isis plays in a couple) had several heavens. These were usually conceived of in layers or parts, corresponding to the layers of the astral plane. In Heliopolis there were 12 layers or planes to their heaven.
— excerpt from Ancient Egyptian Metaphysics by Michael Poe