... People don't see the danger. This is really amazing, isn't it? You'd think they could see it but they can't. If they can't see it even then, then there's no way they can get out. They're determined to whirl around in samsāra. This is how things are. Just talking about simple things like this we can begin to understand.
If you were to ask them, ''Why were you born?'' they'd probably have a lot of trouble answering, because they can't see it. They're sunk in the world of the senses and sunk in becoming (bhava). Bhava is the sphere of birth, our birthplace. To put it simply, where are beings born from? Bhava is the preliminary condition for birth. Wherever birth takes place, that's bhava.
For example, suppose we had an orchard of apple trees that we were particularly fond of. That's a bhava for us if we don't reflect with wisdom. How so? Suppose our orchard contained a hundred or a thousand apple trees... it doesn't really matter what kind of trees they are, just so long as we consider them to be ''our own'' trees... then we are going to be ''born'' as a ''worm'' in every single one of those trees. We bore into every one, even though our human body is still back there in the house, we send out ''tentacles'' into every one of those trees.
Now, how do we know that it's a bhava? It's a bhava (sphere of existence) because of our clinging to the idea that those trees are our own, that that orchard is our own. If someone were to take an ax and cut one of the trees down, the owner over there in the house ''dies'' along with the tree. He gets furious, and has to go and set things right, to fight and maybe even kill over it. That quarreling is the ''birth.'' The ''sphere of birth'' is the orchard of trees that we cling to as our own. We are ''born'' right at the point where we consider them to be our own, born from that bhava. Even if we had a thousand apple trees, if someone were to cut down just one it'd be like cutting the owner down.
Whatever we cling to we are born right there, we exist right there. We are born as soon as we ''know.'' This is knowing through not-knowing: we know that someone has cut down one of our trees. But we don't know that those trees are not really ours. This is called ''knowing through not-knowing.'' We are bound to be born into that bhava.
Vatta, the wheel of conditioned existence, operates like this. People cling to bhava, they depend on bhava. If they cherish bhava, this is birth. And if they fall into suffering over that same thing, this is also a birth. As long as we can't let go we are stuck in the rut of samsāra, spinning around like a wheel. Look into this, contemplate it. Whatever we cling to as being us or ours, that is a place for birth.
There must be a bhava, a sphere of birth, before birth can take place. Therefore the Buddha said, whatever you have, don't ''have'' it. Let it be there but don't make it yours. You must understand this ''having'' and ''not having,'' know the truth of them, don't flounder in suffering.
- Ajahn Chah http://www.ajahnchah.org/book/Flood_Sensuality1.php