Learning that meditation is a mix of samhadi and insight, they are not really separate practises, but part of the same practise. Two sides of the same coin. A lucid serenity.
Sometimes the mind is in the deep stillness and peace of samhadi, and sometimes it is investigating, learning, knowing, clearly-seeing, comprehending. They work together to purify the mind.
I remember hearing in a dhamma talk that the Buddha said samatha (serenity) and vipassana (clear-seeing) are the two trusted messengers to admit into the city of consciousness. But there are also five trouble-makers to keep out of the city. These are: greed, ill-will, stagnation, agitation, and doubt. If those get into consciousness, it will become disturbed.
So one keeps out the five hindrances. And welcomes in the two trusted messengers.
Who is the guard at the gate? It is mindfulness.
I heard in another dhamma talk that a fully enlightened being may still experience longing and aversion in the mind, but the difference between them and someone who isn't enlightened, is that although greed and anger may occasionally arise for them, there is nowhere in the mind for it to land and take root. So nothing becomes of it.
There are sensations: sights, sounds, tastes, smells, touch, ideas and thoughts. And they feel either pleasant or unpleasant. We like the pleasant feelings, and dislike the unpleasant ones. This leads to craving for more of what we like and less of what we dislike. But if we can let go of it before it becomes the stories we tell ourselves about this and that. Before we identify with it and cling to it, before it becomes a sankhara. Perhaps that is the non-grasping or non-clinging part.
Eventually the art of non-clinging or letting go gathers a momentum of its own, becomes a powerful sankhara, continually weakening the hold of the defilements: greed, hate, and delusion on the mind. Till eventually the fetters are broken for good, and then there is cessation, freedom from suffering.