I want to propose a few presumptions about what the IS-BE is. I welcome disagreement because I certainly don't know if these things are true. These are things that Farsight has hinted at but we don't really know (and Courtney probably doesn't really know either because it hasn't been fully communicated to him. I'm sure there are also things they're holding back . . . assuming that Farsight isn't a giant disinfo psyop . . . that's always an uncomfortably probable possibility)
*The IS-BE is not the soul. When we're talking about a Soul, we're talking about an eternal exigency of "God" - the prime creator and governor of the universe that has administered itself a source of individuality. A being that possibly simply does not "remeld" back to God unless by its own free will if it's ever possible at all. It exists outside the universe. It co-creates the universe.
*The IS-BE is more physical. While it isn't bound by the same kinds of rules we know for our bodies in terms of time and space, it also isn't some amorphous omniscient field that pervades all space and time. It is a physical substance that may exist in a different form of matter than what we're familiar with. It is detectable, even at its fringes by the fringes of our current tech.
*The IS-BE transforms through material experience. I don't think the IS-BE just experiences reality for fun or some ephemeral nostalgia. I think the IS-BE probably goes through physical life to solve real problems and create real options for itself as an IS-BE. Transforming the shape of the body it interfaces with probably influences the shape of the bodies it *can* take. Kind of like if you were to take a big room full of wires, and hook them up a certain way for a setup of inputs and outputs . . . the wires removed and then hooked up again would only be familiar with the specific input-output system you gave it. Let me explain a bit more.
The greys were transformed. But it doesn't sound like they were abducted from human bodies, and then implanted into grey bodies. It sounds like they were first transplanted, and gradually shifted into their intended "grey" form through genetic engineering and acclimatization. This is probably what is happening with "hubrids." They are being gradually transitioned to human-like entities but under the same mental blocks that prevent them from rebelling against slavery.
*The IS-BE is a localized shell. I think it was Russel Targ that coined this idea of "non-local perception" in a banned TED talk. But I wonder if that phrase does a disservice to how we are to understand the IS-BE. Perhaps it's not really non-local, but moreso vastly connected via the interstellar field of shared consciousness. This probably fits the increasingly popular (and perhaps seeded) term: "Mycelial network"
*The IS-BE is vulnerable to overload, particularly electrical. And this is the raw electrical of our current technology. This might be the reason behind electrical storms (I mean think about this for a minute. We're told that lightning comes from clouds rubbing each other . . . does that make complete sense to you? Where's the data behind that?) We know that electrical overload causes memory loss for people today. In fact it's still used as a "therapy" . . .
*The IS-BE is "out of phase" with our matter. This has already been discussed. Courtney has mentioned this in the past in his conversations with Harvey. It also matches with the Lacerta Files and Alien Interview. Entire civilizations can exist in alternate phases of matter from our own, but the IS-BE has its own particular phase.
*The IS-BE is a "UFO" . . . I suspect that the technology that makes advanced UFOs fly is probably more similar to how an IS-BE works. They don't travel through space by pushing something against something else. They travel through space by redefining their own internal particle dynamics. It's really a form of teleportation but pure teleportation is too problematic. You too easily come out the other end in a jumble (like in the movie "The Fly") - fast movement is basically redefining location instance by instance because that allows for a more gradual shift where the particles can continually be accounted for.
*The IS-BE has "merge-morphic" properties. I don't think that things remove the individuality of IS-BEs. But I think that certain exchanges between IS-BEs can at least temporarily bond them in a strong way.
*The retroactive effect. The IS-BE has "fragment morphic" properties. Just like they can be temporarily merged, they can also be temporarily fragmented. This is the real concept of reincarnational trauma. And probably the program that keeps many IS-BEs enslaved is a sort of combination of these principles: fragmenting IS-BEs and then merging them in a lopsided way. So that individuality is lost and instead their corrupted definition of self causes them to simply be product of mass control, identifying more with their controlling substrates.
*The IS-BE is not really a separate concept of physics but a sort of iteration of the same or similar principles. Einstein's relativity basically talks about how energy is mass, space is time, space is energy . . . a sort of combination of everything that simply diverges based on various influences. But consciousness is probably also a player in this physics theory. What we call space-time is like space-time-energy-thought. Scientologists talk about the MEST or "matter energy space time" but maybe it's the "mext" or "mecst", matter, energy, consciousness, space, time.