"Prāṇāyāma is said to be the union of Prāṇa and Apāna. It is of three kinds—expiration, inspiration, and cessation. They are associated with the letters of the (Samskṛṭ) alphabet 1 (for the right performance of prāṇāyāma). Therefore Praṇava (Om) only is said to be Prāṇāyāma. Sitting in the paḍma posture, the person should meditate that there is at the tip of his nose Gāyaṭrī, 2 a girl of red complexion surrounded by the numberless rays of the image of the moon and mounted on a hamsa (swan) and having a mace in her hand. She is the visible symbol of the letter A. The letter U has as its visible symbol Sāviṭrī, 2 a young woman of white colour having a disk in her hand and riding on a garuda (eagle). The letter M has as its visible symbol Sarasvaṭī, 2 an aged woman of black colour riding on a bull, having a trident in her hand. He should meditate that the single letter—the supreme light—the praṇava (Om)—is the origin or source of these three letters A, U, and M. Drawing up the air through Idā for the space of sixteen māṭrās, he should meditate on the letter A during that time; retaining the inspired air for the space of sixty-four māṭrās, he should meditate on the letter U during the time; he should then exhale the inspired air for the space of thirty-two māṭrās, meditating on the letter M during that time. He should practise this in the above order over and over again.

"Then having become firm in the posture and preserved perfect self-control, the yogin should, in order to clear away the impurities of the Sushumnā, sit in the paḍmāsana (paḍma posture), and having inhaled the air through the left nostril, should retain it as long as he can and should exhale it through the right. Then drawing it again through the right and having retained it, he should exhale it through the left in the order