Each of the four Vedas—Ṛg, Yajur, Sāma, and Atharva—unfolds in a broadly similar fourfold structure, moving from outward ritual to inward contemplation. At the foundation stand the Saṁhitās, the collections of hymns, mantras, and ritual formulas. These verses are addressed to various deities and are meant for recitation or chanting in sacrificial contexts. The Ṛgveda Saṁhitā preserves metrical hymns to deities such as Indra, Agni, and Soma, while the Sāmaveda Saṁhitā largely reshapes Ṛgvedic verses into melodies for liturgical singing. The Yajurveda Saṁhitās, in their different recensions, combine mantras with ritual directions, and the Atharvaveda Saṁhitā gathers hymns, prayers, and spells concerned with healing, protection, and domestic welfare. In this way, the Saṁhitā layer embodies the living sound-body of Vedic religion.

Surrounding and interpreting this core are the Brāhmaṇas, extensive prose works that serve as ritual exegesis. These texts lay out the procedures for sacrifices, explain the use and placement of the mantras, and weave in mythological narratives to illuminate the symbolic logic of each rite. They describe major sacrificial performances and articulate a theology in which precise action, word, and intention are bound together. Traditional examples include the Aitareya Brāhmaṇa of the Ṛgveda, the Śatapatha Brāhmaṇa of the Yajurveda, and the Gopatha Brāhmaṇa of the Atharvaveda. In the Brāhmaṇa stratum, the ritual universe is mapped in detail, and the sacrificial arena becomes a microcosm of the cosmos.

From this ritual world, the Āraṇyakas mark a turning toward interiorization and contemplative insight. Often associated with forest-dwelling sages, these “forest books” stand between the outward focus of the Brāhmaṇas and the philosophical intensity of the Upaniṣads. They offer symbolic and allegorical readings of the sacrifices, treating ritual elements as supports for meditation rather than merely as external acts. Meditative practices and contemplations on cosmic correspondences appear here, sometimes as later sections of Brāhmaṇas and sometimes as closely related, semi-independent texts. In this layer, the sacrificial fire begins to be understood as an inner fire, and the ritual journey becomes an inward pilgrimage.

The Upaniṣads form the culminating stratum, often embedded as the final portions of Brāhmaṇas or Āraṇyakas. These texts turn decisively to questions of ultimate reality, the nature of the self, and the possibility of liberation. Through dialogues, teachings, and reflective inquiry, they explore Brahman as the ground of all being and Ātman as the innermost self, and they probe the deeper meaning that underlies ritual practice. Major Upaniṣads are traditionally linked to specific Vedas—for example, the Aitareya to the Ṛgveda, the Chāndogya to the Sāmaveda, the Bṛhadāraṇyaka and Īśā to the Yajurveda, and the Muṇḍaka and Māṇḍūkya to the Atharvaveda. Taken together, Saṁhitā, Brāhmaṇa, Āraṇyaka, and Upaniṣad trace a continuous movement from sacred sound and action toward insight into the nature of reality itself.