24. The inflated vital air then passes in many ways, through the holes of the entrails inside the body, and extends to and fills all the pores and canals of the frame from top to bottom.
25. These then receive different appellations, according to their course through the several, and are denominated as the five fold vital airs of prána, apána, samána, udána, and vyána; by them that are skilled in science of pneumatic. (The prána-váyu is the breathing of the nostrils, the apána is the wind in ano, samána is the air circulating through the whole body, udána is the air of speech, and the vyána is the air let out through the pores of the whole body).
26. All the vital powers reside in the triple lotiform organ of the heart, and thence extend up and down and on all sides like beams from the lunar disk.
27. These vital powers are employed in passing in and out, in taking in and letting out, in rising and falling, and also in moving throughout the body.
28. The prána or air of life is said by the learned to be situated in the lotus formed organ of the heart, which has also the power of moving the eyelids in their twinklings. (Hence one's life time is measured both by the numbers of his breathings, as also by that of the twinklings of his eye).
29. This power some times assumes the form of touch or the feeling of perception, and at others it takes the shape of breath by blowing through the nostrils. Some times it is seated in the stomach for culinary action, and oft-times it gives utterance to speech.
30. What more shall I say, than that it is our lord—the air, that moves the whole machine of the body, as a mechanic models everything by means of his machinery.
31. Among these there are two principal airs, by name of prána and apána, which take their two different courses upward and downward, the one is the breath of life and the other is the vitiated which is let out.
32. It is by watching the course of these airs that I remain quiet at this place, and undergo the vicissitudes of heat and cold, as it is destined to the lot of the feathered tribe.
33. The body is a great machine, and the two airs are its indefatigable mover. It has the sun and moon or the fire and moonlight, shining in the midst of its heart.