> But to get to the real understanding we actually shut down that part, forget what we "know", start from a clean slate.

Close, but not exactly. To start from a clean slate is not very difficult, the trick is to reject some chosen parts of existing knowledge, or more specifically the difficulty is to choose what to reject. Starting from a clean slate you'll end up spending millennia to get the knowledge you've just rejected.

So the overall process of generating knowledge is to look under the streetlight till finding something new becomes impossible or too hard, and then you start experimenting with rejecting some bits of your knowledge to rethink them. I was taught to read works of Great Masters of the past critically, trying to reproduce their path while looking for forks where you can try to go the other way. It is a little bit like starting from a clean slate, but not exactly.