The mind is restless, agitated, and difficult to control. A wise person straightens their mind, just as an arrow-maker straightens an arrow. (From the Words of the Buddha)
Our minds are constantly influenced by our surroundings and easily become unsettled. This makes them difficult to control. So we naturally try to lock ourselves rigidly in place, just to avoid being shaken. However, this is not a very effective approach. After all, the world is constantly changing. Even if you try to lock yourself down to resist change, you will eventually lose to its overwhelming power. It is impossible for you alone to remain unchanged. In fact, no matter how hard you try to hold yourself still, you are already changing on your own.
Arrows used to be made from natural materials like bamboo. When first cut, they were naturally not straight. Therefore, arrow-makers would straighten them so they could be used as proper arrows. However, over time, they would bend again due to the effects of the surrounding temperature and humidity. That is why you have to constantly check their condition and tune them back to straight.
The human mind works the same way. Since it is always changing, we must observe how it shifts and be careful it does not turn in the wrong direction. The important thing here is to avoid fixing yourself to a rigid ideology or a fixed dogma. What is needed is to observe closely and tune yourself each time so that you do not drift the wrong way. Subduing agitation, controlling the mind, and keeping it straight is not about staying fixed—it is, ultimately, about actively adjusting it.