“Vedas are Limitless” (अनन्ता वै वेदा:) is a vedic statement contaiined in the Vedas themselves. A story in the Veda goes like this. A Ṛṣi by name Bharadwāja spent three full lives in learning Vedas. Once Lord Indra appeared before him and asked what he would do if he were to be given a fourth birth. The Ṛṣi replied that he would continue his studies. Thereupon the Lord showed three palmful of sand as having been learnt by him over three years and a big stretch of mountain range representing the extent of Veda which needs to be pursued for completion. Such is the extent of Vedas but what we have with us today is negligible.
At the commencement of Dvāparayuga, the great sage Vyāsa made a methodical arrangement of Veda into four parts – Ṛk, Yajur, Sāma and Atharvaṇa. Each part is a self-contained section dealing with the requirements of mankind, both secular and spiritual. He had appointed four disciples to propagate the four branches of Veda. He had asked Paila to spread Ṛk Veda, Vyśampāyaṇa the Yajur Veda, Jaimini the Sāma Veda and Sumantu the Atharva Veda. Paila divided Ṛk Veda into 21 Śākhās (branches), Vyśampāyaṇa divided Śukla Yajur Veda into 15 śākhās and Kṛṣṇa Yajur Veda into 86 Śākhās, Jaimini divided Sāma Veda into 1000 Chapters and Sumantu divided Atharva Veda into 9 śākhās. Presently what is available is 2 in Ṛk Veda, 2 in Śukla Yajur Veda, 3 in Kṛṣṇa Yajur Veda, 3 in Sāma veda and 2 in Atharva Veda. Each of the Veda has got a regular text of divine incantations called Saṁhita, Teachings on sacrifices called Brāhmaṇam, Mantras that are to be recited in secluded areas called Āraṇyakas and Esoteric teachings called Upaniṣads.
The following are the known Śākhās (Recensions). Ṛk Veda has got Śākala and Bhāṣkala Śākhās, Śukla Yajur Veda has got Kāṇva and Mādyandina Śākhās, Kṛṣṇa Yajur Veda has got Taitirīya, Maitrāyaṇīya and Kaṭha Śākhās, Sāma Veda has got Kauthuma, Jaiminīya and Rāṇāyanīya Śākhās and Atharva has got Śaunaka and Paippalāda Śākhās.
||Śākala, Bhāṣkala, Kauśītakī
||Taitirīya, Maitrāyaṇīya, Kapiṣṭhala-Kaṭha, Kāṭhaka
||Taitirīya, Kaṭha, Śvetāśvatara, Maitrāyaṇīya, Mahānārāyaṇīya
||Ārṣeya, Tavalakāra, Tāṇḍya, Chāndogya, Sāmavidhāna, Devatādyāya, Vamśa, Samhitopaniṣad
||Māṇḍūkya, Muṇḍaka, Praśṇa
Of the above, for Ṛk Veda the only recension available is that of Śākalas. For Kṛṣṇa Yajur Veda, excepting the first, others are available in fragments. Both the Kāṇva and Mādhyandina recensions are available for Vājasaneyī Saṁhitā. The recensions available for Sāma Veda are Jaiminīya and Kauthuma and Rāṇāyanīya in parts. Both the Paippalāda and Śaunaka recensions are available for Atharva Veda.
The available portions of text are summed up as under:
Ṛk Veda – 1028 Sūktas – 10 Maṇḍalas
Kṛṣṇa Yajur Veda – Kaṭha & Māitrāyaṇīya: 4 Kāṇda, 54 Prapāṭhakas, Taitirīya: 7 Aṣṭaka, 44 Prapāṭhaka and 651 Anuvākas
Śukla Yajur Veda – Vājasaneyī: 40 Adhyāyas, 303 Anuvākas
Sāma Veda – Ārcika : 585 Mantras, Uttarārcika: 964 Mantras
Atharva Veda – 20 Kānḍa, 731 Sūktas
The four divisions as Ṛk etc serve to the needs of four priests namely Hotṛ, Adhvaryu, Udgātṛ and Brahman respectively.
The other classification of Veda is into Parā Vidya (Superior Knowledge) and Aparā Vidya (Inferior Knowledge). The former is the part containing the Upaniṣadic lore (otherwise called Jñānakānḍa) and the latter is the part containing the religious lore (otherwise called Karmakānḍa).