"... the most advanced ten percent of knowledge in martial arts is far more difficult to achieve than the first ninety percent..."
That's a very interesting statement.
I agree on a basic level, but I don't think it necessarily implies that YOUR TEACHER cannot teach you that last ten percent.
Many teachers themselves may not know the last ten percent. Some maybe do, some maybe don't.
Not all that KNOW something can TEACH it.
Some things can only be learned, not taught.
So, while this "ten-percent" statement might be true, there might be many not-obvious reasons for it.
The statement seems to tie the advanced learning to "other" teachers, but there is no guarantee that such "others" will be any more, or even AS insightful as the original.
The music spoke to me. I felt compelled to answer.