न वायुक्रिये, पृथगुपदेशात् ॥ ९ ॥
na vāyukriye, pṛthagupadeśāt || 9 ||
na vāyukriye—Not air nor function; pṛthak—separately; upadeśāt—on account of its being mentioned.
9. (The chief Prana) is neither air nor any function (of the organs) on account of its being mentioned separately.
In this Sutra the nature of the chief Prana is discussed. The opponent holds that there is no separate principle called Prana, but that it is only air and nothing else, which exists in the mouth as well as outside. The Sruti also says, “That vital force is air.” Or it may be the combined effect of the functions of all the eleven organs. Just as a number of birds in a cage, when they move, also move the cage, so also the eleven organs functioning together constitute life in the body. So the resultant of these functions is Prana. This is the view of the Sankhyas. Hence there is no separate principle called Prana (vital force).
The Sutra refutes these views and says that Prana is a separate principle, for it is mentioned separately from air and the sense functions. “The Prana (vital force) indeed is the fourth foot of Brahman. That foot shines and warms as the light called air” (Chh. 3. 18. 4), where it is distinguished from air. Again, “From that (Self) are produced the vitai force, mind, and all the organs” (Mu. 2.1.3), which shows that it is not a function of any organ, for in that case it would not have been separated from the organs. The text, “The vital force is air,” is also correct, inasmuch as the effect is but the cause in another form and the vital force is air functioning within the body (Adhyatma). The analogy of the birds in a cage is not to the point, for they all have the same kind of activity, viz, movement, which is favourable to the motion of the cage. But the functions of the organs are not of one kind, but different from one another; and they are also of a distinct nature from that of the vital force. Hence they cannot constitute life. Therefore Prana (vital force) is a separate entity.