What did Buddha mean by the words "tranquillising the bodily formation" in the Anapanasati Sutta? “Here a bhikkhu, gone to the forest or to the root of a tree or to an empty hut, sits down; having folded his legs crosswise, set his body erect, and established mindfulness in front of him, ever mindful he breathes in, mindful he breathes out.
“Breathing in long, he understands: ‘I breathe in long’; or breathing out long, he understands: ‘I breathe out long.’ Breathing in short, he understands: ‘I breathe in short’; or breathing out short, he understands: ‘I breathe out short.’ He trains thus: ‘I shall breathe in experiencing the whole body of breath’; he trains thus: ‘I shall breathe out experiencing the whole body of breath.’ He trains thus: ‘I shall breathe in tranquillising the bodily formation’; he trains thus: ‘I shall breathe out tranquillising the bodily formation.’

This passage is translated with the same words in my native language, but I don't understand what does it mean.
The other English translation translates this as &quot;stilling the body’s motion&quot;. Does &quot;tranquillising the bodily formation&quot; means the same as &quot;stilling the body’s motion&quot;?
"If "tranquillising the bodily formation" means "tranquillising the breath", then why didn't Buddha just said "tranquillising the breath"? – Damocle Damoclev"

"Tranquilizing the formation of body" or "stilling, calming, tranquilizing the construction of body", or "body-constructions", or most accurately "the identification with the intent to experience experience of the body", or "tranquilizing the breathing" or "stilling the body’s motion" or "releasing any inner neuroses manifesting as tensions and jerking in the body" and probably a hundred other ways of putting this are all saying the same thing but from different perspectives.

"Body" [ka ya = k-kha whatsoever], meaning in this case that which an individual considers to be 'his body', is an illusion formed from identification with the conjunction of name and form with consciousness thereof. 

That which constitutes "Form" is different in different spheres of existence. In the human, it is formed at the point where earth (solidity), water (liquidity), fire (heat-and-light), and wind (motion) meet. In other realms the components (which are themselves views of a single phenomena from different perspectives - see: http://buddhadust.net/backmatter/indexes/sutta/an/idx_06_chakkanipata.htm#p41
are merged into the less tangible forms "resistance," "adhesion," "heat" and "light," and "motion" (animation). 

'Breath' here is simply the movement of, or vibration of that light. It is at the point where the breath is calmed, stilled completely, that it is possible to distinguish between consciousness tied down to consciousness of form and consciousness not so tied. 

This is the split of the mangos from the mango tree. 

At that point it is possible, if one is aware that this is the freedom one has been seeking, to drop identification with that consciousness that has form as its object: one is able to see it as "not me" "not mine" "not my self" "not of myself" "other". Not seen as the freedom one seeks, that is temporary freedom; seen it is Nibbana. 

It is for this reason that the statement is made: "Of Bodies, I say Breath is one." 

Seeing, as does the ordinary human being, this body as the issue, the source of pain, an instruction such as "stilling the body's motion" or "releasing any inner neuroses manifesting as tensions and jerking in the body" is a correct instruction for the human level. This would make no sense to a deva of one of the realms above that of manusa where 'body' is perceived as purely light.

The Buddha's Dhamma is spoken of as Timeless because it was so worded that it could be heard with both ears: that of man and that of the devas. 

That's why.