The only immutable thing is mutability
Unlike most philosophical-religious traditions of the West, which emphasize eternal life and the immutable, in China and the rest of Asia, existence was understood as a constant change, expressed by the idea of impermanence (無常 wúcháng).
Buddhism calls it anitya and identifies it as one of the three essential characteristics of existence (Tri Laksana), the other being anattā, insubstantiality or absence of self, and duḥkha, which could be translated as discontent or dissatisfaction.
The Yì Jīng 易經 or "Book of Changes" (more commonly transliterated as I Ching) that appeared at the end of the second millennium BC, gives an account of the way of understanding reality in Ancient China. Conceived as a divinatory book, it understands change as the guiding principle of the universe. In this conception of reality, changes occur cyclically and each state contains the seed of its opposite.
From the same way of understanding the universe were born the Yīn-Yáng Theory 陰陽 and the Theory of the Five Phases 五行 (Wǔ Xíng). These phases or states are not immutable elements, but processes in constant change, in which each state gives rise to the next in a cycle without beginning or end.
The teaching that emerges from this idea of impermanence is that, being all things transient, pretending to cling to them leads inevitably to suffering. The liberation of suffering passes through the acceptance of this transience. Non-existence carries the seed of existence, just as existence carries the seed of non-existence. Says the Dào Dé Jīng 道德 經:
有無相生
Being and Non-Being are mutually engendered
and also:
反者道之動,
The transmutation of the opposites is the movement of Tao,
弱者道之用。
Flexibility is the manifestation of Tao.
天下萬物生於有,
The ten thousand beings are born of Being,
有生於無。
and Being has been born of Non-Being.
and finally:
天地尚不能久,
If Heaven and Earth can not create anything permanent
而況於人乎?
How does man intend to do it?
We, the universe, everything that exists is changeable and perishable. Nothing lasts forever. Humans live in an illusion of stability in which we believe that things last forever: youth, life, friendship, love, health, success... When these things come to an end, we plunge into an abyss of suffering that overcome us because we also tend to imagine it as something lasting. The wise accept change and flow with it, without resistance. When something good comes, he accepts it; when it leaves, he lets it go, without clinging. But when something bad comes, he accepts it too, because he knows it will not last long. The Dhammapada says that "acquiring something entails acquiring the fear of losing it". Accepting that nature is impermanent makes us freer and provides peace to our mind.
But this same impermanence of external phenomena also applies to internal phenomena. There is a short Buddhist story about it:
One day, a young Chan monk said to his teacher with concern:
—I can not concentrate on meditation. As much as I try, I am constantly distracted and my thoughts go back and forth again and again. What I can do?
—Do not worry, it will pass. —The teacher answered without giving importance to it.
The disciple returned to his meditation and continued trying. Later, he returned to his teacher with a big smile:
—I have managed to concentrate and entered into a state of deep calm! It's fantastic!
To this, the teacher replied:
—Do not worry, it will pass.
If all things in nature are changing, unstable, how will our thoughts, emotions or mental states be stable? Joy and sadness are transient; therefore, neither euphoria nor despair have real meaning. We can be happier if, just as we accept joys, we accept sorrows.
Impermanence in martial arts:
Chinese martial arts are characterized by non-opposition of resistance. This is also a way to accept change and to flow with whatever comes next.
First, there are no infallible techniques. This is because real situations are changing. Putting into play a technique that we have trained in a specific situation may not work in a different situation. In combat, everything is in motion, in continuous change. What we expected to work is not effective because the situation has already changed. Accepting this change and adapting to it is the key to success; it is useless to stick to rigid patterns or conceived formulas.
In the application of specific techniques, especially in qín-ná 擒拿 (grip and dislocation), it is essential to know how to adapt, to know how to flow. Suppose we initiate a technique, but the opponent is aware of what we are going to do and opposes resistance, exerting force in the opposite direction to our movement. At this time, we must be able to detect the change and adapt to it. This means to stop struggling. The technique that we were beginning is already useless, because the situation is now different. In this case, we must change the technique; instead of going against the movement of the opponent, go with it and letting his energy help us to execute a new technique.
This is easy to understand in martial training, but it is also applicable to any situation in life, and this is more complicated to understand. It seems that it is hard for us to stop "struggling" with life and learning to flow, because we are used to believe that we control everything, to believe that we can control our life and everything that it involves. But life always has its own plans and, if we want to be happy, we must accept them, be willing to accept the change.
Finally, the Buddhist story we have quoted above can be applied to martial practice or any other area of life, in addition to meditation. There will be days when everything goes wrong and our performance is very poor, but they will pass; and there will be days when we are especially lucid and touch perfection in each technique, but they will also pass. Neither we have to be frustrated by the first ones nor to be proud of the other ones, but to remain calm and in full acceptance of what happens at every moment.