The root "yaj" means "'to worship, honour, adore, etc by means of oblations in sacred fire accompanied by proper vedic mantras'". All types of worship cannot be said to be yajña. Only that type of worship is recognized as yajña which follows the rules laid down by Vedic and Kalpa-sutra texts. Therefore, Yajña should be defined as worship, without idols, of Vedic (and now also Puranic) deities with specific Vedic mantras and oblations offered into sacred fire at proper time either as a part of duty or as a means to obtain something from gods without being stuck with fruits of karma so that spiritual knowledge and salvation is not impeded by worldly karmas. Relatively purer souls take recourse to incessant Japa-yajña which does not seem to follow this karmakāndiya definition, but in fact there is no essential difference, the difference is outward : in replacement of physical fire altar with real Agnideva in body, and of physical oblations with mental oblation, and a host of complicated mantras being replaced with a single mantra which should be chanted 24-hours a day till death.
According to Vedic tradition, yajña was instituted by God for the benefit of mankind so that man could perform various karmas according to karmakāndas, otherwise fruits of karmas stick to the performer of karma and cause rebirths. Thus, performing right karma in proper manner so that the ultimate purpose of human life is not lost, which is attainment of immortality by means of sanātana (eternal) spiritual knowledge. This is the main ideological basis of the institution of yajña. Hence, yajña links right Karma to right Jñāna, both yajñic karma and divine Jñāna being based on Bhakti which is the meaning of most famous of all Vedic mantras, Gāyatri ("...inspire into us such a meditative intellect which remains fixed on Thee"). According to Brahmasutra, one who has got Vairāgya (non-attachment) is free to take resort to sanyāsa irrespective of his/her age, ie is under no obligation to perform karmas and yajñas of a householder. Hence, the ultimate purpose of Yajñas is not to remain immersed in Karmas but to evolve towards real Jñāna. Otherwise, people could perform Karmas without Yajña and remain oblivious of spiritual Jñāna. Leading mortals towards spiritual Jñāna was the main purpose behind the institution of Yajña, and that is why the word Veda implies "Jñāna" and not Karma. But this Jñana could not be attained directly, men needed to perform Karma for living in this world. To make both these ends of Jñāna.
Vedas are intrinsically related to yajña and in this strictly ritualistic context Yajurveda is the most important Veda, because the oblations offered to deities are given with special Yajurvedic mantras known as yājushi, although Gita (Gītā) extols Sāmaveda as the best of all Vedas whose meaning is explained in Brahmasutra of Bādarāyana : a brahma-jñāni is transported to Brahmaloka on the verses of Sāmaveda. Mantras from other Vedas, esp Rgveda and Sāmaveda are also needed in yajña but only for secondary purposes. Yajurveda ("the Veda of Yajus", Yajus is a class of mantra for offering oblations in a Yajña") is the main Veda defining different types of Yajña and their mantras. It is believed that there was only one Veda originally, which Veda Vyāsa divided, because with the regression of Kāla from Satyuga to inferior yugas it became increasingly difficult for a single priest to memorize all these three yajñic Vedas (the very name Veda Vyāsa means one who divided/organized the Veda).
Brāhamana texts are believed to be part of Vedas and not composed by mortals. They are primarily concerned with rules and results of Karmakāndic Yajñas. Many portions of Brāhamana texts are known as Āranyakas and Upanishadas and deal with Jñānakānda.
Besides vedas, six Vedāngas are crucial to proper understanding and performance of Yajñas:
- Shikshā : the science of correct pronunciation of mantras. For Yajurveda, its own Prātishākhya is the detailed Shikshā text, and Yājñavalkya-Shikshā is the shortcut for beginners.
- Chhanda : knowledge of metres
- Vyākarana : grammar, esp the special Vedic rules
- Nirukta : explanation of difficult Vedic words
- Jyotisha : for fixing the proper time for Yajñas
- Kalpa : a collection of Sutra texts which teach details of yājñic ceremonies.
Although Mimānsā do not fall under either Veda or Vedānga, and are enumerated under shat-darshana of Vedic-puranic tradition, they are exclusively related to the nature and results of yajñas related to both Karmakānda and Jñanakānda.
Purva Mimānsā, also called Karma Mimānsā, deals extensively with the philosophy of Karmakāndic yajña, with a view to determine how to achieve Dharma by means of Yajñic Karmakānda. Jaimini gave the Purva Mimānsā darshana with 12 chapters. It is primarily an inquiry into the Brāhmana portion of the Veda. It deals with various yajñas, their purposes and methods. It has a four chapter supplement called sankarsha kanda, by Jaimini. It is also called Madhyama Mimamsa, Madhyama Kanda, Devata Kanda and Upasana Kanda. It deals with purpose of mantras, the nature and essence of devatas, purpose of worshipping devatas.
Uttara Mimānsā by Bādarāyana, also known as Brahmasutra, deals with Jñānakānda portion of Vedas and Brāhmanas. Ādi Shankara's greatest work is a commentary of this text.
Two Basic Types of Yajña
The methods and varieties of Yajña have evolved during ages. There are two main types of yajña related to karmakānda and jñānakānda, the latter known as Brahma-yajña. Last chapter of Yajurveda is the main basis of Brahmayajña, although mantras of Brahmayajña are dispersed throughout the YV, including the sacrificial chapters. In this class similar portions from other Vedas and Vedic texts like Brāhmanas have been put to form the category of texts known as Upanishadas, which literally means "to sit near a guru (for learning the secret Brahmavidyā)".The purpose of both these types of yajña is described in the last chapter of YV, which is more famous as Ishopanishada. Yajñas related to kāmya-karma fall under karmakānda and help the performer to fulfill worldly aims without being tarnished with sin. Hence, such yajñas help in getting over the obstacle of death, while the jñāna-yajña helps in attaining true immortality, by means of giving relief from the chain of death and rebirth in this world (cf. YV, chapter 40).
Types and Tools of Karmakāndiya Yajñas
There are two chief types of karmas : nitya-karma and kāmya-karma. Nityakarma includes 19 vedic rituals which are not to be performed daily but only on certain occassions, besides two daily yajñic rituals Agnihotra and Aupasana to be performed twice daily at dawn and dusk, which have been replaced with sandhyā-vandana and pañch maha-yajña by most of the persons now-a-days who perform them, and even these persons are in a minority. Nityakarma is theoretically compulsory for the twice born. Amont 21 nityakarma yajñas, first seven are known as pāka-yajñas (cooked sacrifice), while next seven are havir-yajñas (burnt oblation) and remaining seven are soma-yajñas.
Kāmya-yajñas are optional, numbering around 400. Complex yajñas need to be performed once in a lifetime. Putrakāmeshti (for getting sons), Rājasuya (royal consecration), Ashvamedha, etc are kāmya yajñas which are optional. Satra-yajña takes 12 years and is for universal good.
Nityakarmas can be divided into (1) daily duties and (2) those duties which occur at certain specific occassions such as shrāddha and are categorized as naimittika karma.
We can understand original significance of yajñic karmakānda only in its wider context. Yajña fulfilled the wishes but absolved the fruits of karmas. But these wishes ought to be according to dharma and not blindly selfish. Literal meaning of the term "Veda" is 'spiritual and eternal Knowledge', and Yajurveda provides the karmakāndic rituals of worship which ultimately lead to such a jnānakāndic Knowledge.
Chapterwise, Yajurveda describes following principal yajñas :
1.-2. : Darsha-paurnamāsa Yajña (New and Full Moon yajña)
3. : Agnihotra (Agni-upasthāna, Chāturmāsya, etc)
4.-8. : Somayajña, which included Agnishtoma, Agnisomiya-Pashuyajña,upānshugra,Ādityagraha)
9. : Vājapeya and Rājasuya
10. : Rājasuya, Sautrāmani
11.-18. : Construction of altars and hearths, especially the Agnichayana and chiti mantras,Rudri,Vasordhara
19.-21. : Sautrāmani : Indra-abhisheka
22.-25. : Ashvamedha
26.-29. : Supplementary formulas for various rituals
30.-31. : Purushamedha, Purushasukta
32.-34. : Sarvamedha, Brahmayajña, Shiva-samkalpa
35. : Pitramedha
36.-39. : Pravargya
40. : Isha Upanishad (Jñana-kānda of YV)
