Ajahn Chah

focused inwards rather than turning towards the world outside.

It's as if you come inside your house.

where all your sense faculties have come together to form one compact unit.

Awareness remains with the breath and over time it will penetrate deeper and deeper inside, becoming progressively more refined.

Ultimately awareness of the breath becomes so refined that the sensation of the breath

You could say either that awareness of the sensation of the breath has disappeared or that the breath itself has disappeared.

Then there arises a new kind of awareness, awareness that the breath has disappeared.

In other words, awareness of the breath becomes so refined that it's difficult to define it.

But really the breath is still there, but it's become so refined that it seems to have disappeared.

Because the mind is at its most refined with a special kind of knowing.

Even though the breath has vanished, the mind is still concentrated with the knowledge that the breath is not there.

As you continue, what should you take up as the object of meditation?

Take this very knowing as the meditation object

In other words, the knowledge that there is no breath.

And sustain this.

You could say that a specific kind of knowledge has been established in the mind.

At this point, some people might have doubts arising because it is here that a vision or a mental image, known as a nimitta, can arise.

There can be many kinds, including both forms and sounds.

It's here that all sorts of unexpected things can arise in the course of the practice.

If mental images do arise, and some people have them and some don't, you must understand them in accordance with the truth.