I had indeed noticed the opposite pairings. What I was curious about was wether, within the further translations, these pairings gain significance as primary manifestations, in a martial sense, of Aiki expressed through the body. In Chinese IP there are 4 primary directions of energy flow and four primary functions, each functions containing at least 2 pf the primary directions. In Chen Tai Chi silk reeling, the training of internal spirals flows through these directions and functions. Why did Ueshiba pick these descriptions specifically? Or could a whole lot of other descriptive combinations of opposites be named?
I apologize for my failing memory but somewhere in the creation myths of Japan is reference to the sword of ice and the sword of fire, two more descriptions of opposite powers. I believe Ueshiba quoted these as well but I believe Chris will have the source far better than I do. If Aiki is the unified state which remains inside the body, is it's manifestation the polar compliment of the type of force the opponent brings to bear?
Sorry that I can't help with the Chinese side of things. I don't have much background in them. However, I put part of your post in bold and underline to reference it. The answer is no. Think of aiki as you all ways being centrally held amidst infinite spirals of opposing forces. External forces are not part of creating that. IP/Aiki = you. Always. All ways.
I loved Dan's analogy of a washing machine motor/agitator. Inside a washing machine, you typically have a central device that has spiraling fins. When the motor runs, it turns that central piece one way, then back the other way. Now, picture having a bar welded onto the top of that piece so that it sticks outwards (middle of bar is welded to top of agitator piece). When the motor turns, one arm goes forward, one arm goes backwards. Grab either or both arms and you are moved by the motor.
Now, replace the motor with a 500 hp engine. When it turns, wham, it's quick and decisive. It turns back the other way in an instant, too. So, if you push or pull or grab that bar, does the engine care? Does the engine have to add polar complimentary force to function? No. Whether you grab the bar with the motor and it just moves you or you grab the bar with the engine and it rips your arms off, the entire functioning system does not really care how you grab, push, or pull.