The most important insight I have learned so far in my life is balance.
The idea came from my study of the nature of change (dynamics). Dynamics is the outcome of positive feedback loops (reinforcing loops) and negative feedback loops’ (counteracting loops, or balancing loops) interaction. Sometimes reinforcing loop is the strongest, producing growth or drop behaviour. But the growth or drop would not continue forever. It would slow down, indicating that counteracting loop becomes dominant. When there is reinforcing loop, there is counteracting loop; when there is larger reinforcing loop, there is larger counteracting loop; when there is strong reinforcing behaviour, there will be stronger balancing behaviour. That seems to be nature of change.
This reminds me of the traditional Chinese philosophy. Traditional Chinese philosophy contained primitive ideas of dynamics(易), positive and negative forces’ interaction (陰陽), balance/moderation(中道、中庸), relationship between extremity and regime shift (物極必反).
Balance is not only about engineering control theory or Socio-Ecological system dynamics. Think about homeostasis in personal health.
It is not only Chinese who notice it, i.e. there is idiom called “Feast or Famine”(時飽時餓，不是太多就是太少，不是極好就是極差，好壞不定的).
From the perspective of society, neither feast nor famine is desired. We usually prefer no more, no less — just — enough, and keeps it forever.
Naturally, while counteracting loop will balance back diverging(偏離) condition of reinforcing loop, due to the inherent delays, the correction may produce big swing as illustrated in Figure (a), or even regime shift (environment changes permanently, old way not works anymore). This may not be desired.
Ideally, we might like to find equilibrium level and stick with it. There are three issues with this ideal: First, it is very hard, if not impossible, to ascertain(確定) equilibrium level accurately; Second, when there is shock, environment changes, equilibrium level changes again; Third, and the most fatal, inherent delays (stocks) can only be reduced but not eliminated completely. Therefore, the best we can do is to minimise the amplitude of oscillation like in Figure (b), so that rise and fall will be in relative peaceful (smooth) way.
In other words, being moderate does not mean we must find the exact middle point(中間點). It would be more like balance the condition back when we detect current condition becomes extreme. There will always be fluctuations — no worry about boring.
This is an era loss of ideology. Communism? Gone. Capitalism? Failing… What else can we refer to?
The problem of ideology/faith is people. People have tendency to like to take a principle to extreme. “Drink water is good for health.” Okay, so to keep healthy, I drink water as much as I can, but then I get sick. Why? “Too much water, water intoxication!” My goodness!
If people must have one single principle to simplify thinking (reasoning), I would recommend moderation.
It is the safest principle, because even if it is taken to the extreme, moderationism is still “moderate in moderation”. Still moderate!
“It can also be recursive in that one should moderate how much they moderate (i.e. to not be too worried about moderating everything or not to try too hard in finding a middle [point]).” from Wikipedia.
And “Moderation is the silken string running through the pearl chain of all virtues” — unknown source.
In the zero-centered multi-dimensional space, moderation can be understood as moving around 0, not too positive (+ve) and not too negative (-ve).
There are many advices like “balance between A and B”, not every A and B is the balance/moderation of what I mean. Moderation is a general principle inducted (not deducted) from many cases of A and B but by no means exhaustive, some may only valid in their particular context while some are really universal and timeless. All inductions are wrong, but some are useful.
Also, moderation does not mean compromise, take middle ground between two opposite positions on fact (e.g. global warming). This is a logical fallacy (http://en.wikipedia.org/wiki/Argument_to_moderation).
Moderation is likely the principle for sustainability.