There's an old chestnut that one can't have thoughts without words. As a visual thinker, I always found this assertion preposterous.
How does one explain the common experience of mathematicians and scientists of awaking to a fully formed revelation, of complexity far greater than the one bounce memory echo of 12x13?
I can think of no other answer than that they are "thoughts". They are thoughts I think in my dream. But they are visual, not verbal thoughts. And verbal thoughts? They are typically "audible" thoughts, I hear them in my head.
It's been reported that what people seldom dream about is reading some text, which is curious. Maybe there's no need for that because brain can dream words directly, as spoken words you hear in your head.
One thing that tends to be the norm for my own dreams, when I'm cognizant enough to remember them: even when they are realistic, they are genuinely surprising.
The other "characters" in my dreams surprise me to no end. "I" struggle to predict how they will react. For example "they" sometimes respond to "me" with witty comebacks that I don't feel like I remotely anticipated, and when I think about it after I wake up, I'm still impressed by their cleverness. It's hard to believe both sides of the conversation could have been generated by my one brain.
Sometimes I'll suddenly notice an inconsistency -- "hey wait a minute, how could Tokyo be an hour's drive away from here?" -- and the world will instantly contort to explain it, in a way that feels both natural and yet totally unanticipated. "Didn't you hear about the earthquake? It accelerated continental drift, creating a land bridge between Japan and North America. Look, here's the latest map!"
My conclusion is that dreams are a kind of generative antagonistic training. Half of my brain is coming up with wild scenarios and modelling complex agents with hidden state, and the other half is perceiving this, reacting to it, and trying to decide if it's real. If it is, the generator wins. If it's not, I realize I'm dreaming, and I usually wake up or at least switch to a new dream.
In addition to being consistent with what dreams feel like to me, this process would help (both parts of) my brain develop a mental model of reality.
Perhaps revelations don't require working memory, but are connections between known things? Hence their instantaneousness. The expression "fully formed" suggests a whole, without steps.