Dear Yong Peng and friends,
I hope you will bear with me, giving some details from the Abhidhamma
commentaries, because without them it is difficult to understand the Co. to
the Raahulovaadasutta.
In the first book of the Abhidhamma (Dhammasangani) § 638, aakaasa is listed
among the derived physical phenomena. There are 28 kinds of physical
phenomena, four of which are the four principle rupas or mahaabhuuta ruupas,
of solidity (earth), cohesion (water), heat (fire) and motion (wind). The
rupas other than these four are the 24 derived rupas, upaadaaruupa. These
arise in dependence on the four great elements. Sound, for example, is a
derived rupa arising in a group of rupas consisting among others of the four
great elements. Sound does not float in the air by itself, it needs the four
great elements and other rupas.
We read about space in the Dhammasangani: <That which is space and belongs
to space (akaasaa gata), is sky and belongs to sky, is vacuum and belongs to
vacuum, and is not in contact with the four Great Phenomena- this is that
form (ruupa) which is the element of space.>
In Buddhaghosa's Commentary to the first Book of the Abhidhamma
(Atthasaalinii, tr as Expositor, 326) and also in Buddhaghosa's
Visuddhimagga (XIV, 63) more details are given as to its function. We read
in the "Visuddhimagga":
<The space element has the characteristic of delimiting matter. Its function
is to display the boundaries of matter. It is manifested as the confines of
matter; or it is manifested as untouchedness, as the state of gaps and
apertures (cf. Dhs . 638). Its proximate cause is the matter delimited. And
it is on account of it that one can say of material things delimited that
'this is above, below, around, that>
Speaking of details, I also found that my medical knowledge of the digestive
tract is lacking. But the "Visuddhimagga" in the description of "Foulness of
the Body" meditation subject could help me. For some commentaries one needs
also Ayurveda (Co to Siivaka sutta about bile and phlegm).
Nina.