Originally posted by PeterR
Are the skills of uke directly applied to the skills of Tori. Not really. At the most simple level, tori's job is to maintain balance, uke's is to lose it.
I disagree with the comment above. I may be "splitting hairs" but perhaps not.
Uke's job is to give a sincere, committed attack and attempt to regain balance when it is taken by tori. This gives tori the chance to learn "fitting and timing" within the kata. Tori's job is to have good posture, movement, etc. while "taking" uke's balance and fitting the technique with uke's recovery attempt. This enables both participants to learn by "feel" the real principle of "using the opponent's force."
The ability of uke to do this in a relaxed manner without worrying about the "fall" leads to sensitivity in feeling what is happening. This, in turn, leads to learning how to be tori by taking ukemi from tori.