On the grand universal scale it makes sense, everything lives, dies, and returns to its source. But how does it apply on a personal level? Or, a martial level for that matter?
Maybe, it is merely karma. Everything we give out returns to us in the course of time, as a matter of karmic balance. In Buddhist theory, this does not just apply to the here and now, but applies to the evolutionary aspects of reincarnation as well. But the Tao is more abstract. Perhaps less specific in this regard.
Personal and emotional equilibrium is another possibility. We return to ourselves and our balanced emotional state after every encounter or event. In martial terms this would be exertion, followed by the restful (yet aware) state of being. It would be about constantly recalibrating one's Mind, per se, or even the physical body itself. (Realigning to nature itself?) This is a return to the "unchanging aspects" of oneself.
Lastly, it could all be about cycles--or circles--so prominent in eastern thought. We always return to the beginning of the circle. We evolve in cycles and return to beginner's mind in all we do. In jiu-jitsu, the circle is paramount, and we always complete the circle of a technique and return to the starting point.
And each morning we return to a new day, and study more and more about the nature of ourselves and all around us.