About This Answer
How calm should the mind be before taking up the body for contemplation? Ajahn Dtun answers that it should be peaceful at least to the point where it is as if empty of thinking. There may be lightness of body and mind, rapture, the happiness of concentration, or equanimity; let the mind rest in that peace. When it withdraws and thinking starts up again, that is the time to take up the body for contemplation.
We have to be wise to the workings of our own mind and see for ourselves whether the concentration is sufficient for the work. He compares it to testing a knife: to know how sharp it is, try cutting vegetables or meat. If it cuts through easily, it is sharp; if not, go back and sharpen it.
The measure is simple. If the mind stays with the body as the object of contemplation, the concentration is sufficient. If it thinks about all kinds of things outside the practice, mindfulness and wisdom are not yet strong enough; stop contemplating and go back to strengthen samādhi.