I believe that I have crossed the threshold between "can't" and "can" on the violin. Seventeen or so years of diligent practice, and a few startling breakthroughs have taught me the "where" and "how" of addressing a lot of violin playing difficulties that I used to have. I realized today that I have forgotten what "can't" feels like on the violin, though "don't" and "won't" are still alive and festering.
But I feel what "can't" feels like on the piano. The connection between what my fingers touch and how they feel is not yet formed, but I understand the goal of "can" because I can recognize "can't." I imagine that at some point--perhaps in a few years, or maybe even in a few months--I might not remember what "can't" feels like on the piano. "Can't," unless it is related to concrete physical limitations, has more to do with not knowing how to do something than not being able to do it. Remembering the feeling of "can't" actually motivates and excites me, because it gives a kind of definition to the road that stretches ahead.
I remember when I couldn't touch type (I learned how at the age of 22 or 23, when I went to typing school), but I don't really remember what it physically feels like not to be able to touch type.
I remember when I couldn't swim, but I don't remember what it feels like not to know how to swim or ride a bicycle, or drive a stick shift.
Я определенно понимаю чего он значит не мочь прочитать русского, ή ελληνικά, 或者, but I don't remember what it feels like not to be able to read English.