Perhaps a simpler take ...

yin ... ok, yang ... ok. floating bridge ... a state that transcends yin and yang, or more precisely, the state where yin and yang have disappeared, a singularity of pure potential.

a seed in the ground - no yin, no yang. and then spring and pop! the seed comes to life. the yang activity of expansion quite apparent, dominating the yin activity of contraction for a time of growth. but spring gives way to summer and autumn and eventually yang gives way to yin, the plant withers and dies ... ah, but a seed, a seed in the ground - no yin, no yang.

the floating bridge ... no yin, no yang ... a singularity of pure potential ... the source of aiki.