What is mindfulness (sati) and how does one practise it?

Mindfulness (sati; the Sanskrit counterpart is smṛti, “memory”) is recollection: the ability to keep in mind what is happening and what you are doing, without slipping into forgetfulness. In the suttas the term sati carries several different senses:

• Memory and recall (MN 53): the ability to remember what was said or done long ago (for example, “to remember deeds of the past”).
• Keeping in mind: reminding oneself of the important principles of the Dhamma, holding on to the reference points of practice.
• Presence of mind and awareness (mindfulness / awareness): direct perception of what is happening in the present moment without distraction, clarity of mind.

Sati is the first of the seven factors of awakening. In the Noble Eightfold Path right mindfulness (sammā-sati) is the seventh factor. In this context it is defined not as presence in the moment in general, but through the practice of the four foundations-domains of mindfulness (satipatthanas - body, feelings, mind, mental constructs - MN 141, MN 10). The full formula runs: the practitioner contemplates the domain “ardent (ātāpī), clearly comprehending (sampajāno), mindful (satimā), having put away covetousness and displeasure towards the world” (MN 10). So “non-judgemental observation” is not quite an accurate translation. The practice includes telling the wholesome from the unwholesome: in the section on dhammas, for example, the contemplator knows how a hindrance arose, how it is abandoned and how it does not arise again.

One can start practising recollection with the first steps of MN 118 (the Anapanasati Sutta), taking the breath as the domain of the body: sit down, straighten the back, know a long breath as long and a short one as short, then experience the whole body and calm bodily activity. The mind will keep switching to various other inner phenomena (emotions, sensations, thoughts). Noticing this, one should bring recollection back to the chosen object. In everyday affairs - walking, eating, talking - the same coupling works, but the emphasis shifts to sampajañña, clear comprehension of what you are doing.

Sati has its own image in the canon - the gatekeeper. In SN 35.245 the gatekeeper of the city is explicitly called a designation for mindfulness, and in AN 7.67 the disciple “with mindfulness as gatekeeper” abandons the unwholesome and develops the wholesome. The gatekeeper-sati, in the end, decides what to let into our life.

Where to read: MN 10, MN 118, MN 141.