Two things happen in the middle of big projects, I’ve noticed.
One of them is the mid-project motivational slump: that period where you hate the project, can’t see any point in completing the project other than to demostrate your incompetence and hubris to the world at large, and can’t imagine why you chose to start the project when you could have written, oh, I don’t know, a nice conventional linear narrative about competent Anglophone spacemen bringing civilisation to someone in sore need of it, goshdamn. The project taunts you. Touching it blackens your fingers, like an old fireplace in a foreclosed cottage.
(There’s a dissertation update, for them as was lookin’.)
The second is what I’m starting to think of as conceptual accretion. In the early phases of any project, you’re getting your sources and inspirations in order, keeping them together in a big tank somewhere, sloshing around near the front of your brain, to see what happens when you smoosh ’em and smash ’em together. Some of those ideas and facts and twistings might merge or mix, and you start getting a nice solid bolus of… shit, I don’t even know what this precursor material is called, but I can tell you mine comes in boluses, and you keep building them up and compacting them down with more layers of material, like one of those ice-cored snowballs they warned you about at primary school after that boy lost his sight in one eye, until suddenly some certain mass or density is achieved, and criticality occurs.
At this point, any new idea you encounter may well be sucked into the project by the increasingly powerful gravity well focussed on your original idea-bolus. The first few days of this phenomenon are deceptively heartening, as they offer what seem to be new angles on the original target, but after a little while you end up with an accretion disk of rubble the size of a solar system orbiting around an idea so dense and obsessed upon that it is obscured by its own singularity, which not even the light of your own thoughts able to escape unscathed.
Come to think of it, Thing Two may well explain Thing One.