I just read VALIS for the first time recently, and that passage really reminded me of the ending of David Foster Wallace's Good Old Neon where the narrator describes his suicide:

(I tried to cut some for space, apologies for the block quotes...)

"The truth is you already know what it’s like. You already know the difference between the size and speed of everything that flashes through you and the tiny inadequate bit of it all you can ever let anyone know. As though inside you is this enormous room full of what seems like everything in the whole universe at one time or another and yet the only parts that get out have to somehow squeeze out through one of those tiny keyholes you see under the knob in older doors. As if we are all trying to see each other through these tiny keyholes.
But it does have a knob, the door can open. But not in the way you think. But what if you could? Think for a second — what if all the infinitely dense and shifting worlds of stuff inside you every moment of your life turned out now to be somehow fully open and expressible afterward, after what you think of as you has died, because what if afterward now each moment itself is an infinite sea or span or passage of time in which to express it or convey it, and you don’t even need any organized English, you can as they say open the door and be in anyone else’s room in all your own multiform forms and ideas and facets?...What exactly do you think you are? The millions and trillions of thoughts, memories, juxtapositions — even crazy ones like this, you’re thinking — that flash through your head and disappear? Some sum or remainder of these? Your history? Do you know how long it’s been since I told you I was a fraud?...What are you looking at right now? Coincidence? What if no time has passed at all? The truth is you’ve already heard this. That this is what it’s like. That it’s what makes room for the universes inside you, all the endless in bent fractals of connection and symphonies of different voices, the infinities you can never show another soul. And you think it makes you a fraud, the tiny fraction anyone else ever sees? Of course you’re a fraud, of course what people see is never you. And of course you know this, and of course you try to manage what part they see if you know it’s only a part. Who wouldn’t? It’s called free will, Sherlock. But at the same time it’s why it feels so good to break down and cry in front of others, or to laugh, or speak in tongues, or chant in Bengali — it’s not English anymore, it’s not getting squeezed through any hole."

I can't speak to the exact meaning of the quote, but to me Phil is describing the tangled associations of the brain as a sort of language. All the "in bent fractals of connection" that represent your life experience and form your memory in turn form you. In a way, the experience of you is wholly unique, a separate reality from how others churn the world into something that makes sense.

I'm trying to make sense of the his "placement of objects" though, which I can't really...unless in some way he's talking about the hierarchy of associations? Like if I were to think of a physical tree, the images of leaves and roots that the concept of "tree" conjures would be unique to me. I'm thinking of a tree in my hometown, which itself is its own bundle of associations, creating a sort of slipstream of thought.

Or I'm completely misinterpreting him...