It's easy to imagine that knowledge transfer is at worst lossy, losing a little detail each time it is written down or told to another person.
But with each jump from brain to document (Writing is Hard), document to brain, or brain to brain, knowledge is reassembled — omitting, emphasising, or changing details altogether.
This is bad news if we want to build a library of canonical documents, which is difficult for many other reasons. (Hitting a Moving Target)
The good news is that transferring knowledge — figuring out how to articulate it and understand it — improves our mental model of that topic each time. (Knowledge is Personal)