War is like fire
Fire grows and spreads because it creates the conditions to do so by itself. A small local fire turns up the temperature and drives away moisture in its immediate surroundings, creating the conditions for combustion. Once its immediate surroundings are lit on fire, the conditions are created in the layer surrounding that, and so on. In this way, a spark, an ember blown by the wind, a cigarette tossed carelessly out of a car, can start a vast and uncontrollable conflagration. Most living beings in the forest are burned to death, and the few that escape can never return, because the very conditions for life have been destroyed.
War is like this. A quarrel arises between neighbours; people are hurt; others vow revenge and take up arms; more people are hurt; and so on.
It may be that the fire was started deliberately. Or it may be that someone benefits from the fire, and pours fuel over it to accelerate it. The same is true of war.
Fire, and war, are examples of destructive processes that grow and propagate because of an in-built positive feedback mechanism. Fire begets more fire, war begets more war.
The process can be stopped early; it takes a while before the feedback mechanism is well established. Anyone who has ever started a fire knows that at first it takes some tender care and steady feeding of small amounts of fuel before it sets off on its own. So there is a lesson about war here too: pay attention to the small, smoldering wars around us, and pour water on them before it's too late.
There is a point, however, when the fire spirals out of control. The same is true of war. As a rule of thumb, if it's in the news, it's too late. The public is a heavy, clumsy animal with very poor sight, overwhelmed by noise.
What can one do? Pay attention. Don't be part of the feedback mechanism. Avoid making sparks, tossing cigarettes. Don't start a fire in a forest, however small. Don't use fire in dry, hot weather. Put out any fire you see as soon as possible. And if someone is pouring fuel over the fire, don't help them.
As a community, be prepared. Create fire breaks so the fire doesn't spread. Have a crew of well-trained and well-equipped firefighters at the ready.
Use common sense, but first make sure you develop that common sense, which means that you internalize all the possible strategies to counter the feedback mechanism. Then you can act quickly should the need arise, because speed is of the essence.
What about war? How do you develop a common sense to prevent war from growing and spreading? What are the sparks, the cigarette butts that start a war? What is the feedback mechanism, the conditions of temperature and dryness that make war surge uncontrollably? What firebreaks can we build as a community? Who is pouring fuel over the fire of war, and can we stop them? And how can we help the beings that are burning to death in the forest of war?
A metaphor is a tool, and it is only useful if you pick it up and do something with it. Please consider these questions seriously, and try to answer them. Pick one up now, and work with it. They are not easy questions, and if you persist, almost certainly you will be surprised by what you discover. But it's a wonderful discovery, when you find yourself no longer reading about the fire in the paper, but actually carrying water to it.