However, there is more to be said on this topic. For instance, I think it's important to talk about exactly why it is that two things need a common medium or "matrix" in order for them to come into relation with each other at all. The key to this question lies in a simple observation: that in order for me to know about another thing at all (let alone interact with it in a concrete way), some evidence of that thing must present itself to me. This evidence means that I and that thing have at least "crossed paths," for the very fact that I am aware of it means that we both exist in a realm of being in which I can at least encounter the "traces" of that other thing. If I and that thing didn't have a common "space," I would not be able to conceive of this object, let alone know about it or interact with it.
At a very fundamental level, things like "space" and "time" are examples of the kind of matrix in which I can be situated together with an object. In other words, I share in common with essentially anything or anyone I have encountered the facts that we a) exist in space, and b) exist in time. This commonality I have with things makes it possible for me to encounter and perceive them--it is precisely because I share "space" and "time" in common with these things that we can come into awareness of each other at all.
But notice something here: you never see space and time. Though you may see objects that occupy a space and occur at a time, I can only infer the actual existence of space and time from these objects, and never from direct perception. But of course this makes sense--because I can only come to perceive things in space and time, I can never perceive space and time themselves. This is much like you never actually see light--you only ever see objects illuminated by light. Like light, space and time are the means by which I see--and thus they are "too close" for me to discern by themselves.
But if it is true that space and time--two qualities I have in common with all things in the universe--are examples of media through which I see other things, is it true for other commonalities? For instance, is it true for colors or shapes or tones? I would say that it is. In other words, I never actually see "yellow"--though it may seem counter-intuitive, I only ever see things that are yellow. Though I may see a banana, a lemon, or a glass of orange juice, the most I can say is that they share something in common; if my sight actually were directed to the color "yellow," then yellow would be a thing. But yellow isn't a thing--it's a "form" of things, (to use a Platonic or Wittgensteinian term; they both apply here) a way in which things can be similar to each other. And just like the other "forms" of space and time, though I never actually see yellow, yellow gives me the ability to see things that are (i.e. exemplify) yellow.
Thus, the forms of space, time, colors, sounds, and shapes are all means by which I see, and as such I never actually see them in themselves. But I would also say that redness, hardness, and quietness are matrices, media, or "between-spaces" in which I am situated with their relevant objects, and by which I can come into contact with them. A form such as this lays out a "stage" on which interactions between objects can take place. Thus, I can encounter colored objects on a "colored" stage, a loud sound on a "loud" stage, etc.
Though it sounds odd, the fact that I exist in a medium, matrix, or "between-space" of "greenness" means that I, along with a green object, also share in that greenness. But this should be obvious--when I look at a frog, there is green in me, in range of my vision. When this happens, there is a green spot in my vision, and as such I share "green-ness" in common with that frog. In fact, I would say that all perception is like this: in order for me to see something, I must share the matrix, the "stage" of the object's form with it--we must both exist in a common medium that embraces all things which share that form.
To put it even more simply, you could say that each form (whether it be space, time, a color, or something more weird, like "squareness") exists equally in all things that exemplify that form. Blue exists in all things that are blue, squareness exists in all things that are square, etc. But one might also point out that two or more things in a representative relationship (like a picture and its object) also share a form--the form of whatever is in common between what the picture and what is pictured (Wittgenstein called this the "form of representation" in his Tractatus Logico-Philosophicus). Thus, whenever something is a picture of another thing, and by extension whenever something resembles another thing, there is a form, a between-space, a matrix that embraces and exemplifies itself in both of them. In the case of human perception, what I experience through vision, what you experience through vision, and what we both see all share this kind of form, and thus what is "common" between each of the three phenomena comes to show itself.
I am not alone in this idea. The eighteenth-century thinker Johann Wolfgang Von Goethe's Theory of Colors points out:
"The eye owes its existence to light. From an auxiliary, sensory apparatus, animal and neutral, light has called forth, produced for itself, an organ like unto itself; light has called forth, produced for itself, an organ like unto itself; thus the eye was formed by light, of light and for light, so that the inner light might come in contact with the outer light. At this very point we are reminded of the ancient Ionian School, which never ceased to repeat, giving it capital importance, that like is only known by like."
I think that the phrase "like is only known by like" is essential here. I can only ever come into contact with something if I am somehow the same as that thing, if we both "spring" from the same matrix or medium. With regard to color, this means that I must already exist on a "stage" corresponding to color in order to see it at all. So too with space, time, roundness, etc.--in order for me to see spatial, temporal, or round things, I must exist also in the between-space that shares exemplifies qualities. But an interesting consequence emerges from this--even if I am not, say, a dog, a child, or a woman, my ability to come into contact with those things means that I must share something very fundamental in common with them. In other words, since I exist in a between-space with another person, we both spring from the same matrix; we are connected at the very depths of our being. Though I might look different from, say, Regina Spektor, the fact remains that our beings spring from the same depths--we are both exemplifications of deeply fundamental forms.
This brings me back to a point I made in my "The Fire Between Two" post from last month: the fact that I am different from a woman makes my encounter with her a revelation of eternity. Our differences make it so that, in order for us to become intimate, we must descend clear down to the level where the differences spring. In other words, the more marked the difference, the more profound the revelation that comes when I find the medium that exists between us. And to reiterate a point I made in that post, this is why it is so important to defend the role of difference (sexual or otherwise) in our experience of sacredness.
But another consequence emerges from this: if I exist in a medium, matrix, or between-space toghether with all things, then in a very meaningful sense I am connected to all things in my depths. To connect with all things doesn't need a "stepping-over" of boundaries--as D&C 88:67 states, when I am single to the glory shining from within me and from behind the world of my day-to-day life, I "comprehend all things." This takes a willingness to see past the appearances of the world, to go past "seeing" entirely by connecting to the matrices, forms, and between-spaces that exemplify themselves in the things we encounter through sense. By doing this we can truly experience existence as "all in all"--all things contain all things, and I can see anything in anything when I look to the "between" that exemplifies itself in the things of my life (see this link to portions of the Avatamsaka Sutra, a lengthy but supernally beautiful Buddhist scripture that's based on just this idea).
I get the impression that the most fundamental form--that which is between all of us and all things--is what we call the Kingdom of God, the Celestial Kingdom, or what have you. Unlike those who would have you believe it exists on some planet next to some star or other, I suggest that this Kingdom exists very close at hand. It is all around us and within us; it shines through our world, our minds, and our bodies, and yet the darkness in them doesn't comprehend it. To see it you must learn to see without seeing, to know things by the glimmers of an obscure light that shines through them. And of course, it shows up most clearly when we love, for love reveals the invisible fullness between us and all things.
And when we learn to see this Kingdom and its glory, we realize that this world is but the barest reflection of the fullness contained therein. We then begin to suspect that the whole chain of beings and worlds is nothing more than a series of double-facing mirrors; I am a reflection of something higher, and that higher thing is a reflection of something still higher. But in this endless chain of reflection and re-reflection, what is unchanging is not what we see, but what we are. Behind the endless ladder of worlds, we may perhaps discern the unchanging presence of the "between," for after everything else, it is the form of a single Kingdom and its indwelling love that shows itself through the kaleidoscope of images in our world (and all others).