Dear Bhante Kumara and Rob,
In the Way of Mindfulness, Ven. Soma:

<Samudaya-dhammanupassi va kayasamim viharati = "He lives contemplating
origination-things in the body." Just as the air moves back and forth
depending on the smith's bellows' skin, the bellows' spout, and appropriate
effort, so, depending on the coarse body, nasal aperture, and the mind of
the bhikkhu, the respiration-body moves back and forth. The things beginning
with the (coarse) body are origination (kayadayo dhamma samudayo]. The
person who sees thus, is he who lives contemplating origination-things in
the body.

Vayadhammanupassi va kayasmim viharati = "Or he lives contemplating
dissolution-things in the body." In whatever way, the air does not proceed
when the bellows' skin is taken off, the bellows' spout is broken, and the
appropriate exertion is absent, even in that same way, when the body breaks
up, the nasal aperture is destroyed, and the mind has ceased to function,
the respiration-body does not go on. Thus through the ending of the coarse
body, the nasal aperture and the mind there comes to be the ending of the
respirations [kayadi-nirodha assasapassasa-nirodho]. The person who sees in
this way, is he who lives contemplating dissolution-things in the body. >

Nina: It shows that as long as we live there is breathing, and this is
conditioned by citta. It shows conditions. Our life depends so much on
breath but we cling to it.

These phrases are repeated all the time. One has to realize momentary
arising and falling away, but also the dependent origination: so long as
there is ignorance, there is the cycle.
See the following in the section on the postures:
<Samudaya-dhammanupassi = "Contemplating origination-things." Also
dissolution-things are included here. Origination and dissolution should be
dwelt upon by way of the fivefold method beginning with the words: "He,
thinking 'the origination of materiality comes to be through the origination
of ignorance,' in the sense of the origin of conditions, sees the arising of
the aggregate of materiality.">
The following from the Tiika:

<In the same way he sees the arising of the aggregate of materiality through
the origination of craving, karma and food, in the sense of the origin of
conditions, and also while seeing the sign of birth [nibbatti lakkhana
passanto pi]. He sees the passing away of the aggregate while thinking that
the dissolution of materiality comes to be through the dissolution of
ignorance, in the sense of the dissolution of conditions, and through the
dissolution of craving, karma and food, in the same way, and while seeing
the sign of vicissitude [viparinamalakkhana].

For the arising of the materiality-aggregate ignorance, craving, karma and
food are the principal reasons. But these are not all. As it is said that
one sees the arising of the materiality-aggregate when beholding also the
rebirth-sign or the bare origination state called the integration-succession
[upacaya santati] of the various material forms [rupa] becoming manifest in
the conscious flux [saviññanaka santana], owing to ignorance, craving,
karma, and nutriment, and from consciousness [citta] and the process of
caloricity [utu], the knowledge of arising is fivefold.

Similarly the knowledge of passing away or ceasing is fivefold. The sign of
vicissitude or change is the bare state of dissolution [bhanga sabhava]
called impermanency [aniccata]. >

Nina.
-------------

> In Pali@yahoogroups.com, Kumaara Bhikkhu <venkumara@...> wrote:

>> samudayadhammaanupassii vaa kaayasmi.m viharati,
> vayadhammaanupassii vaa kaayasmi.m viharati,
> samudayavayadhammaanupassii vaa kaayasmi.mviharati.
>>
>> What does that look like to you? Does it seem quite plain to you
> that it's speaking of the rising and passing away of phenomena, in
> this case, with regard to the body?

>> The commentary however, in commenting on "vayadhammaanupassii"
> went to the point of speaking about when the body breaks up (kaaye
> bhinne).