Yoga Sutra - Samādhi Pada 1.34
प्रच्छर्दनविधारणाभ्यां वा प्राणस्य ॥३४॥
pracchardana-vidhāraṇābhyāṃ vā prāṇasya ||34||
Or [stability of mind is gained] by exhaling and retaining the breath.
Sūtra I.32 indicated that the obstacles to yoga can be overcome by fixing or concentrating the mind on an object, and the next few sūtras outline various options and methods for accomplishing this. Patañjali has already presented Īśvara as an object of concentration in the form of recitation of the sound oṁ, and by placing Īśvara first on the list of options and dedicating so many sūtras to him, Patañjali has clearly prioritized an Īśvara-centered form of meditation. The following sūtras up to I.39 all also contain the particle vā, or. Thus they are all alternative and optional techniques for fixing the mind and, as with the Īśvara verses, are to be read as referring back to I.32, that practice on one object eliminates the distractions to yoga. One or more of them might be more suitable to a particular person, time, and place, says Śaṅkara, hence the options. Here, Patañjali lists another method of fixing the mind: through the control of breath, prāṇa. Although breath control can also bring stability of mind, the “or” introducing this sūtra does not indicate that the previous sūtra is optional, Vācaspati Miśra hastens to add. The “or” is in relation to the following sūtras, not the previous one—friendliness, compassion, etc., from I.33 must be cultivated in all instances.
Exhalation, pracchardana, says Vyāsa, is the expulsion of the stomach air through the nostrils by means of special techniques, and retention, vidhāraṇā, is the restraint of the breath. These special techniques, elaborates Vācaspati Miśra, involve slowing the exhalation and lengthening the retention of the breath within the body according to the texts delineating such matters (discussed here in II.50). Obviously, point out the commentators, inhalation is not specified in this sūtra because it occurs naturally—retention can only follow inhalation; thus, all three aspects of breath control involved in prāṇāyāma are intended: recaka, exhalation; pūraka, inhalation; and kumbhaka, retention. Vijñānabhikṣu holds that since sūtra II.29 situates prāṇāyāma, breath control, as the fourth in a series of the eight limbs of yoga, its separate mention in this sūtra as a prop for gaining control of the mind, a feature of the higher limbs of yoga, is for the advanced practitioner.
As a result of such breathing techniques, the body becomes light and the mind steady, says Hariharānanda. If the breath is subdued, the mind also becomes so because the two are intimately connected. Thus these techniques produce steadiness of the mind and one-pointed concentration. Hariharānanda notes that during the exhalation and retention of breath, the nerves of the body relax. He specifies that the chest and body should be kept still so that the process of breath control is undertaken by the abdominal muscles. At a certain stage, retention and exhalation occur in a unified fashion; no separate effort need be taken for each. After prolonged practice, a happy feeling of lightness spreads over the whole body. But the most important point for Hariharānanda is to practice meditation along with breath control. Otherwise, he warns, the mind can get more disturbed rather than less so. Only when one-pointed concentration of the mind is cultivated along with the prāṇāyāma does the mind become free from vṛttis and approach samādhi states.