anãpãna mindfulness meditation

What are the thirty-two kinds of knowledge in mindful workers? Here a bhikkhu, gone to the forest or to the root of a tree or to an empty place sits down, having folded his legs crosswise, set his body erect, establishing mindfulness in front of him, ever mindful he breathes in, mindful he breathes out. (1) Breathing in long, he knows 'I breathe in long;' (2) or breathing out long, he knows 'I breathe out long.' (3) Breathing in short, he knows 'I breathe in short;' (4) or breathing out short, he knows 'I breathe out short.' (5) He trains thus 'I shall breathe in acquainted with the whole body;' (6) he trains thus 'I shall breathe out acquainted with the whole body.' (7) He trains thus 'I shall breathe in calming body fabrication;' (8 ) he trains thus 'I shall breathe out calming the body fabrication.' (9) He trains thus 'I shall breathe in acquainted with happiness;' (10) he trains thus 'I shall breathe out acquainted with happiness.' (11) He trains thus 'I shall breathe in acquainted with pleasure;' (12) he trains thus 'I shall breathe out acquainted with pleasure.' (13) He trains thus 'I shall breathe in acquainted with mind fabrication;' (14) he trains thus 'I shall breathe out acquainted with mind fabrication.' (15) He trains thus 'I shall breathe in calming mind fabrication;' (16) he trains thus 'I shall breathe out calming mind fabrication.' (17) He trains thus 'I shall breathe in acquainted with mind;' (18 ) he trains thus 'I shall breathe out acquainted with mind.' (19) He trains thus 'I shall breath in gladdening mind;' (20) he trains thus 'I shall breathe out gladdening mind.' (21) He trains thus 'I shall breathe in concentrating mind;' (22) he trains thus 'I shall breathe out concentrating mind.' (23) He trains thus 'I shall breathe in liberating mind;' (24) he trains thus 'I shall breathe out liberating mind.' (25) He trains thus 'I shall breathe in contemplating impermanence;' (26) he trains thus 'I shall breathe out contemplating impermanence.' (27) He trains thus' I shall breathe in contemplating fading away;' (28 ) he trains thus 'I shall breathe out contemplating fading away.' (29) He trains thus 'I shall breathe in contemplating cessation;' (30) he trains thus 'I shall breath out contemplating cessation.' (31) He trains thus' I shall breathe in contemplating relinquishment;' (32) he trains thus 'I shall breathe out contemplating relinquishment.' [Commentary on introductory paragraph]