Lao-tze used the phrase “reversing is the movement of the Tao,” to explain what he thought was a universal law of nature. This meant that if any one thing swings too much to the right of a pendulum, then it is only natural and can surely be expected to swing to the opposite side with the same momentum. “When a thing reaches one extreme, it reverts from it.” And, “if anything develops certain qualities, those qualities invariably revert to become their opposites.” This universal law could also explain how too much of any one thing would be bad. An example of this being over eating.
Food is understandably good and necessary for the human body to live, but too much food can cause ill health and ultimately disease and death.
This balance that Lao-tze talked about can be applied to relationships as well. In my own life I have been in relationships in which my partner has been overly passive. This dynamic sets up a natural tendency for me to be more aggressive. I, therefore, need to pay close attention so as not to become overly aggressive. Just the existence of one person being too passive sets the stage for imbalance in the other direction. The mere existence of opposition is, in itself, a result of two existing polarities that are rooted in one another.
This reversal of movement in nature is there to protect us from harm, or from being too out of balance. In other words, the system is there in order to help right the situation. It is said that yin-yang, when out of balance, will “no longer counterbalance each other, and disease arises as a result.” In the ancient times, doctors had the intention of keeping their patients well so that yin-yang were always able to keep one another in check. Once the imbalance reached a certain point, the body itself was no longer able to manage things appropriately.