The Yajurveda is primarily a hand-book of Vedic rituals. It has two branches: the Kṛṣṇa Yajurveda and the Śukla Yajurveda. The former is also known as the Taittirīya, and has, like other Vedas, the Saṁhitā, the Brāhmaṇa and the Āraṇyaka sections.
The Taittirīya Upaniṣad comprises the three chapters, 7 to 9, of the Āraṇyaka section. The 10th is the well-known Māhānārāyaṇa or Yājñikī Upaniṣad.
These three chapters are called Śīkṣāvallī, Brahmānandavallī and Bhṛguvallī respectively.
It begins with the oft-repeated and well-known śāntimantra (invocation for peace) śaṁ no mitraḥ.
Then there is a reference to Śikṣā or Śīkṣā, the science of phonetics.
Since the meaning of Vedic mantras is closely dependent on their correct pronunciation and intonation, a knowledge of this science is very necessary.
The Upaniṣad then describes five kinds of meditation, relating the letters of the Vedic mantras to things like pṛthvī or earth, agni or fire, ācārya or teacher, mātā or mother and so on. It also gives the special fruits accruing from such meditations.
To achieve anything worthwhile in life, a sound mind and a sound body are necessary.
Hence, in the next anuvāka, certain japas of mantras and homas in consecrated fires are prescribed for the benefit of those desirous of wealth, learning, intelligence and wisdom. Towards the end, the teacher of the Vedic gurukula prays that a large number of students come to him for education, since it is through them that knowledge and culture will spread in the society later on.
Then is described the meditation on the four vyāhṛtis—bhūḥ, bhuvaḥ, suvaḥ and mahaḥ—as identified with the earth, the fire, the sky, the air, the sun, the Vedic mantras, the vital prāṇas in the body and so on, along with their fruits.
The fourth vyāhṛti, mahaḥ, was discovered by the sage Māhācamasya, as identical with Brahman/Ātman.
The Vedic metre paṅkti has five lines. A Vedic sacrifice also has five parts. By considering the worlds such as the earth, the deities such as Āditya, the elemental objects such as water, the vital airs such as prāṇa and so on as five-fold (‘pāṅkta’), the contemplation gets elevated to the level of a Vedic sacrifice and results in the meditator getting identified with Hiraṇya-garbha (the World-soul, an aspect of Brahman). This is the gist of the seventh anuvāka.
The next anuvāka describes meditation on Oṁ in various ways and the fruits thereof.
Even after returning home and settling down as a householder, the Vedic student is expected to continue svādhyāya (self study) and pravacana (teaching the Vedas to worthy students). This helps in preserving and spreading dharma for the good of the society. This is the main purport of the ninth anuvāka.
The tenth anuvāka is a mantra (a sacred text meant for meditation) discovered by (or attributed to) the sage Triśaṅku. It gives a description of the experience of the spiritual oneness with creation.
The next anuvāka, practically the last in this Śīkṣāvallī, contains the famous advice of the ācārya (Vedic teacher of the gurukula) to a disciple who has completed his training and is about to depart for home. The gist of this (convocation) address may be given as follows:
Speak the truth and follow dharma in your life. Treat your parents, the teacher and the guests that come to you, as if they are gods. Practise the good and abhor the evil. Imitate only the good conduct even from me. Treat the sagacious brāhmaṇas with respect and honour them properly. Give gifts to the needy, considering it as a sacred duty. When in doubt about actions or behaviours seek the guidance of the wise elders. Treat the transgressors of dharma with a balanced attitude of firmness and kindness. This is the command.
This chapter starts with the two well-known śāntimantras or peace invocations—śaṁ no mitraḥ and saha nāvavatu—as part of the Upaniṣadic text.
‘Brahmavid āpnoti param,’ ‘One who knows Brahman attains the Supreme’—this is the primary teaching of this chapter. This Brahman is satya (truth), jñāna (knowledge) and ananta (infinite). One who realises it in his own heart, will become omniscient and will get all his desires fulfilled.
Then there is a description of the evolution of this world from the Ātman (same as Brahman) through the five elements, food and up to the human being.
In the anuvākas 2 to 5, there is a description of the five types of ātmās or puruṣas (individual beings) called respectively—annamaya, prāṇamaya, manomaya, vijñānamaya and ānandamaya (ātmās or puruṣas). They are actually the five aspects of the jīvātman (the individual Self in bondage) associated with the five kośas or sheaths, viz., the physical body, the vital airs and sense organs, the mind, the intellect, and ajñāna (nescience, responsible for bondage and transmigration). One has to transcend them to realise one’s true nature, i.e., Brahman/Ātman.
The Ātman (or Brahman)—according to the sixth anuvāka—created this world out of himself and also entered into it as its inner Self. Hence, all that exists here is he, the Ātman or Brahman.
Therefore, one who gets established in Brahman as his own Self, attains fearlessness. He enjoys bliss since Brahman is bliss. This is the main purport of the seventh anuvāka.
The next anuvāka describes that all the activities in this created world, like the sun rising or the wind blowing, take place by being strictly regulated by Brahman, of whom even the god of death is afraid!
Then there is—in the eighth anuvāka—a very interesting calculation of brahmā-nanda (the bliss of attaining Brahman) by taking the mānuṣa-ānanda (ideal happiness of an ideal human being) as the base. According to this, brahmānanda is 1020 (i.e. 1 followed by 20 zeros!) times that of ideal human happiness. In effect it just means that the bliss of attaining Brahman is infinite.
The last anuvāka of this chapter declares how the knower of Brahman is freed from all fears and apprehensions. Nor is he subject to regrets and self-condemnation.
This chapter starts with the request of Bhṛgu-Vāruṇi to his father Varuṇa to teach him Brahman. Stating that Brahman is that from which all beings are born, in which they live, and to which they ultimately return, Varuṇa advises his son to find it out through tapas (inner peace and concentration of mind).
Every time Bhṛgu returns, after a brief period of tapas, with a solution, he is sent back by Varuṇa, since what he has discovered is only the lower truth. After thus eliminating anna (food), prāṇa (life-force), manas (mind), and vijñāna (intellect), he finally arrives at ānanda (bliss) as Brahman, the ultimate cause of the world.
The text then expatiates upon the importance of anna or food. It must not be derided. It should not be refused when offered. It should be increased so that it can be offered to the hungry souls. Similarly when someone asks for shelter, it must not be denied.
This is followed by some more meditations on the internal organs like the hands and feet or the external objects like rain or animals, as Brahman, which results in the acquisition of fame or intellectual faculties or even objects of luxury and enjoyment.
The Upaniṣad closes with a beautiful description of a knower of Brahman freely roaming about the worlds and bursting with joyous songs.