Sati - ‘Awareness’
Sampajanna - ‘ The constant thorough understanding of impermanence’
Ātāpī sampajāno satimā - ‘Ardent with awareness of mind and body at the level of sensations and with constant thorough understanding of impermanence’
-And how, meditators, does a meditator understand thoroughly? Herein, meditators, a meditator knows sensations arising in him, knows their persisting, and knows their vanishing; he knows perceptions arising in him, knows their persisting and knows their vanishing; he knows each initial application (of the mind on an object) arising in him, knows its persisting and knows its vanishing. This, meditators, is how a meditator understands thoroughly.
In the above statement, it becomes clear that one is sampajana only when one realizes the characteristic of impermanence, and that too on the basis of experience of sensation (vidita vedana). If it is not realized through vedana, then it is merely an intellectualisation, because our fundamental contact with the world is based on sensation. It is directly through sensation that experience occurs. The statement further indicates that sampajana lies in experiencing the impermanence of vedana, vitakkavedana, vitakka (the initial application of the mind on an object) and sanna (perception). Here we should note that impermanence of vedana is to be realized first because according to the Buddha-
Everything that arises in the mind is accompanied by sensation.
The second explanation given by the Buddha of sampajanna emphasises that it must be continuous. He states-
And how, meditators does a meditator understand thoroughly how does a meditator understand thoroughly?? Again, meditators, a meditator in going forwards and backwards understands impermanence thoroughly, in looking straight ahead and sideways understands impermanence thoroughly, in bending and stretching understands impermanence thoroughly, in chewing and drinking, eating and savouring understands impermanence thoroughly, in wearing the double fold robe, alms bowl and single fold robe (in the case of a monk), understands impermanence thoroughly, in attending to the calls of nature understands impermanence thoroughly, in walking, standing, sitting, sleeping and waking, speaking and remaining silent understands impermanence thoroughly.
The emphasis on continuity of sampajanna is very clear. One should develop constant thorough understanding of impermanence.
With proper understanding of the teaching of Buddha, it becomes clear that if this continuous sampajanna consists only of the thorough understanding of the processes of walking, eating and other activities of the body, then it is merely sati. If, however, the constant thorough understanding includes the characteristic of arising and passing away of vedana (sensations) while the meditator is performing these activities, then this is panna. This is what the Buddha wanted people to practise.
In order to put sampajanna into practice, the technique of vipassana meditation becomes a constant. Every moment aware, every moment equanimous. Ardent in awareness of sensations. Working equanimously, giving importance to the subtler sensations as they arise and pass. Equanimous with the solidified sensations as they arise and pass. Aware of the apparent reality of solidified sensations, developing samadhi to become aware of the subtlest reality of subatomic sensations arising and passing with great rapidity. Aware, equanimous, this is how we practice vipassana, this is how we practice sampajanna.
Referenced from the Vipassana Research Institute (VRI)