The descriptions of the others must be sought in that work.--When this steadiness of posture has been attained, "regulation of the breath" is practised, and this consists in "a cutting short of the motion of inspiration and expiration" [ii. 49]. Inspiration is the drawing in of the external air; expiration is the expelling of the air within the body; and "regulation of the breath" is the cessation of activity in both movements. "But [it may be objected] this cannot be accepted as a general definition of 'regulation of breath,' since it fails to apply to the special kinds, as _rechaka_, _púraka_, and _kumbhaka_." We reply that there is here no fault in the definition, since the "cutting short of the motion of inspiration and expiration" is found in all these special kinds. Thus _rechaka_, which is the expulsion of the air within the body, is only that regulation of the breath, which has been mentioned before as "expiration;" and _púraka_, which is the [regulated] retention of the external air within the body, is the "inspiration;" and _kumbhaka_ is the internal suspension of breathing, when the vital air, called _práṇa_, remains motionless like water in a jar (_kumbha_). Thus the "cutting short of the motion of inspiration and expiration" applies to all, and consequently the objector's doubt is needless. Now this air, beginning from sunrise, remains two _ghaṭikás_ and a half[440] in each artery[441] (_náḍi_), like the revolving buckets on a waterwheel.[442] Thus in the course of a day and night there are produced 21,600 inspirations and expirations. Hence it has been said by those who know the secret of transmitting the _mantras_, concerning the transmission of the _ajapámantra_[443]-- "Six hundred to Gaṇeśa, six thousand to the self-existent Brahman, "Six thousand to Vishṇu, six thousand to Śiva, "One thousand to the Guru (Bṛihaspati), one thousand to the Supreme Soul, "And one thousand to the soul: thus I make over the performed muttering." So at the time of the passing of the air through the arteries, the elements, earth, &c., must be understood, according to their different colours, by those who wish to obtain the highest good. This has been thus explained by the wise-- "Let each artery convey the air two _ghaṭís_ and a half from sunrise. "There is a continual resemblance of the two arteries[444] to the buckets on a revolving waterwheel. "Nine hundred inspirations and expirations of the air take place [in the hour], "And all combined produce the total of twenty-one thousand six hundred in a day and night. "The time that is spent in uttering thirty-six _guṇa_ letters,[445] "That time elapses while the air passes along in the interval between two arteries. "There are five elements in each of the two conducting arteries,-- "They bear it along day and night; these are to be known by the self-restrained.