It's the elaborated core insight. You should be able to take it and with minimal adoption use it in your thinking and writing.
When you have the component idea fully understood - chunked in your mind it'd be easier for you to build on that knowledge and to arrive at new insights.
Other way to think about it achieving effect of conversation with your notes where they can transfer the full understanding of idea of your past self to your future self. You need to be able to cross the inferential distance that has opened over time.
One way to internalize this is evergreen notes should be written as if you were explaining the idea to a friend
Past experience
Most of my notes so far can be classified as pointers to other things or reminders about ideas - fragmented notes. And pointers get lost, so the value of notes degrades over time.
I've rarely had the experience described when I read it and feel like communicated with other mind