What is Yoga, as per the Maitraiyani Upanisad
A six-fold (sadanga) yoga is recommended in the Maitraiyani UpaniÓsad. A description is given of Brahma, the One in the sun, in the cooking fire, and in the heart. Realization of the unity of self with the limitless.
One is attainable by six yogic practices: restraint of the breath pranayama, pratyahara, dhyana, dharana, tarka, and samadhi [Mait. Up. 6:18].
17. In the beginning Brahman was all this. He was one, and infinite; infinite in the East, infinite in the South, infinite in the West, infinite in the North, above and below and everywhere infinite. East and the other regions do not exist for him, nor across, nor below, nor above. The Highest Self is not to be fixed, he is unlimited, unborn, not to be reasoned about, not to be conceived. He is like the ether (everywhere), and at the destruction of the universe, he alone is awake.
Thus from that ether he wakes all this world, which consists of thought only, and by him alone is all this meditated on, and in him it is dissolved. His is that luminous form which shines in the sun, and the manifold light in the smokeless fire, and the heat which in the stomach digests the food. Thus it is said:
‘He who is in the fire, and he who is in the heart, and he who is in the sun, they are one and the same.’
He who knows this becomes one with the one.
18. This is the rule for achieving it (viz. concentration of the mind on the object of meditation): restraint of the breath, restraint of the senses, meditation, fixed attention, investigation, absorption, these are called the sixfold Yoga. When beholding by this Yoga, he beholds the gold-coloured maker, the lord, the person, Brahman, the cause, then the sage, leaving behind good and evil, makes everything (breath, organs of sense, body, &c.) to be one in the Highest Indestructible (in the pratyagatman or Brahman). And thus it is said:
‘As birds and deer do not approach a burning mountain, so sins never approach those who know Brahman.’
19. And thus it is said elsewhere: When he who knows has, while he is still Prana (breath), restrained his mind, and placed all objects of the senses far away from himself, then let him remain without any conceptions. And because the living person, called Prana (breath), has been produced here on earth from that which is not Prana (the thinking Self), therefore let this Prana merge the Pratia (himself) in what is called the fourth’. And thus it is said:
‘What is without thought, though placed in the centre of thought, what cannot be thought, the hidden, the highest-let a man merge his thought there: then will this living being be without attachment.’
20. And thus it has been said elsewhere: There is the superior fixed attention (dharana) for him, viz. if he presses the tip of the tongue down the palate and restrains voice, mind, and breath, he sees Brahman by discrimination (tarka). And when, after the cessation of mind, he sees his own Self, smaller than small, and shining, as the Highest Self, then having seen his Self as the Self, he becomes Self-less, and because he is Self-less, he is without limit, without cause, absorbed in thought. This is the highest mystery, viz. final liberation. And thus it is said:
‘Through the serenity of the thought he kills all actions, good or bad; his Self serene, abiding in the Self, obtains imperishable bliss.’
21. And thus it has been said elsewhere: Sushumna, going upwards from the heart to the Brahmarandhra, serving as the passage of the Prana, is divided within the palate. Through that artery, when it has been joined by the breath held in subjection, by the sacred syllable Om, and by the mind absorbed in the contemplation of Brahman, let him proceed upwards, and after turning the tip of the tongue to the palate, without using any of the organs of sense, let greatness perceive greatness. From thence he goes to selflessness, and through selflessness he ceases to be an enjoyer of pleasure and pain, he obtains aloneness…..kevalatva, final deliverance.
And thus it is said:
‘Having successively fixed the breath, after it had been restrained, in the palate, thence having crossed the limit, the life, let him join himself afterwards to the limitless Brahman in the crown of the head.’