Phillip Smith said: "Interesting discussion. Maybe the fault (as so often) lies in the translation. I prefer to think of "working with the natural" as unforced movement. Sure the joint locks eventually but it doesn't have to be through a movement against the joint, joints will always lock at the end of natural range of motion and perhaps that is what is meant by working with rather than against the joint."
I do not really want to comment against Mr. Smith, especially since I think he is advocating a very common (wide-spread) view of Aikido waza. I would like to refer to this view in general, not personally.
Firstly, I do not feel Kisshomaru's statement is in need of such tweaking and/or spin in order for it to make sense. What he is saying is not so mysterious. If it appears to be it is for another reason. The need for such tweaking or spin comes not from the esoteric nature of what is being said but rather from the pressure of making something that is utterly false appear to be true or appear to be true in most circumstances.
Also: Movement on Nage's part does not have to be forced in order for an Uke's joint to travel beyond its range of motion.
Secondly, if one wants to say that Aikido moves joints naturally to the limit of their range of motion, one isn't going to fulfill the second part of Kisshomaru's statement -- which goes to Aikido's uniqueness. Nearly every other art -- Japanese and non-Japanes alike - manipulate joints naturally beyond their limited range of motion.
Thirdly, any healthy joint is going to experience a locked sensation and/or even pain (i.e. nerve sensation) whenever it is moved beyond its natural range of motion. That is not a translation issue; it is just science. If someone is being thrown, say with Kote Gaeshi, and the joint is staying within it's natural range of motion, then they are not really being thrown with Kote-Gaeshi as much as they are by some other Kokyu-Nage and/or as much as they are throwing themselves (which is always more common that one would like to admit). Again, other martial arts do these very things as well (even the throwing of oneself part).
In my opinion, if you are going to look for Aikido's uniqueness, it is in its spirituality (Osensei's and not Kisshomaru's) and in how that spirituality might effect one's waza and state of being.
A while ago, another post inspired me to write the following on where I would say Aikido's uniqueness truly lies -- from our web site: