This is my understanding and it won't be as detailed as I want it to be since I'm at work this morning.
Plato was spot on with his understanding of the world of ideas, imo. His allegory of the cave perfectly fits the reality of the situation we find ourselves in on earth. All we see in physical earth life reality is a shadow, an outward reflection of what's on the other side of us. Does that make it unreal? Depends on your definition. Right now we are inhabiting a monkey body in a realm of 'stuff'. Since our physical body is made of this same 'stuff' as the rest the world then, yeah, our current experience of reality can be considered 'real' as long as we are experiencing it.
The world of ideas is the dimension directly adjacent to us (hyperspace). If this is true then it means it's as close to our dimension as the 2 dimensional plane is close to us. Enter the whole flatland analogy which is highly appropriate. A 2 dimensional creature has no height, only length and width and can only move backward and forward, left and right. We 3 dimensional creatures, as a by-product of dimensional advantage, can see the entire world of a 2 dimensional creature effortlessly. There would be no place in their flat world they could hide from our 3 dimensional eyes since we are looking 'into' their world from a higher dimension. Ever wonder why there are so many eyes in psychedelic art and trip reports? I make the claim is a similar phenomenon only increasing all the dimensions by 1.
The next part is even more difficult to accept and that's my theory that you don't think your thoughts, your thoughts think you. For instance, if the DMT space is a quantum soup of probabilties and if all possibilities CAN exist but only a select few undergo what scientists call 'the formality of actually occuring', then it stands to reason that EVERYTHING already exists and pre-exists all creation in thought or non-form. Micky Mouse the cartoon character was not created by the human Walt Disney. Instead, in an opposite way of looking at it, Mickey Mouse is a CONCEPT from the world of ideas that wished to manifest itself in Earth's history and culture, and chose the human Walt Disney to be 'channeled' through. All creativity, whether scientific or otherwise, can be considered a form of channeling. You're becoming an open conduit for ideas to flow into the Earth, but your not generating the ideas in your brain any more than your radio is generating the radio waves you hear.
Ever hear of meme theory? It's this concept that thoughts are like their own organisms and seek to propegate themselves by spreading to more people. Christianity is a classic example of a meme going global. No one alive today has ever met Jesus to know anything factual about the man, but millions of people accept the religion that bears his name on thought alone. The plethora of gods and goddesses, demons and devas from all corners of the world's ancient myths I think are poor attempts at explaining this concept that ideas have their own freestanding existence. Ares may not have existed as an actual personage of flesh and blood during classical Greek times, however war sure as hell did and he was the god of war. Ares as an idea is an idea of war, which clearly existed then and still exists now, thus it's a meme that has propegated itself over countless ages of humanity. There are countless examples like this.
This is all my wild speculation so don't take anything I ever say as fact, but since you mentioned Plato this is my understanding into his works since my psychedelic voyages.
All posts are from the fictional perspective of The Legendary Tek: the formless, hyperspace exploring apprentice to the mushroom god Teo. Tek, the lord of Eureeka's Castle, is the chosen one who has surfed the rainbow wave and who resides underneath the matter dome. All posts are fictitious in nature and are meant for entertainment purposes only.