The post Rig-vedic philosophy shows two trends, discernible in the Brahmanas and in the Upanishads. Though they belong to the Vedas they are considered apart from the Vedas, as they express notions(ideas) that have a character and quality of their own.
They are mainly textbooks of ritual and prayer for the priests, serving as commentaries on the Vedic hymns, describing in detail the sacrificial ceremonial, and giving many curious explanations both linguistic and legendary of the origin and meaning of the rituals.
The Brahmanas stress the importance of prayer, sacrifice, ritual, liturgy, formalism, textualism, and emphasize the observance of caste and the ashramas sacrificial rites are regarded as all powerful, controlling the processes of nature and even the gods. This led to an elaborate formulary and to the domination by the Brahmin priesthood who conducted vast and elaborate rites and attached cosmic significance to the smallest minutiae. Says the `shatpatha brahmana, 'verily there are two kinds of gods: the gods themselves who are assuredly gods, and the priests who have studies Vedic lore'.
Each of the Vedic samhitas has its Brahmanas, which reflect as it were the character of the samhita with which they are associated. The Brahmanas also often give the name to the related Upanishad. The Rig-vedic Brahmanas include: the Aitareya Brahmana perhaps the oldest of them all. It deals principally with the great soma sacrifices and the different ceremonies of royal inauguration. The Kausitaki, also called the Shankhayana or the Ashvalayana Brahmana, contains much material common to the Aitareya and treats of various sacrifices.
The Brahmanas of the Yajur-veda include: the Taittiriya Brahmana of the Black Yajurveda the origin of which is linked with the name of the saga Yajnavalkya. The Shatapatha Brahmana belonging to the Vajasneyi samhita of the White Yajur-veda, is an important source of information for sacrificial ceremonies, theology and philosophy. Next to the Rig-veda it is the most important work in Vedic literature, and is ascribed to Yajnavalkya. It is found in two recensions, namely, the Madhyamdina and the Kanva.
The Brahmanas of the Sama-veda are eight in number. Included among them are: the Prauda Brahmana, consisting of twenty-five sections, hence also called the Pancha-
vimsa. It contains the famous vratya-stoma ritual by which non-Aryan converts were admitted into the Aryan fold. Shad-vimsa Brahmana, so called because it was added to the twenty-five sections of the Prauda. The Sama-vidhana Brahmana, the third Brahmana of the Shama-veda, devoted entirely to magic. It gives the chants to be used for various spells. Tandya, the most important Brahmana of the Sama-veda, sometimes confused with the Prauda. It is concerned with sacrifices in general, and with particular rites like the sattras, vratya-stomas, and others. The Adbhuta Brahmana, a manual treating of omens and anrugies, marvels and miracles. It is sometimes regarded as part of the Shadvimsa and is often classed with it. The Chhandogya Brahmana is famous for the Upanishad named after it.
The Atharva-veda has only one Brahmana, namely, the Gopatha. It is a very late work and is composed largely of material gathered from previous sources, including the Shatapatha and the Aitareya.