The Brahad Aranyaka Upanishad has two explanations to offer. In one place, it says:
“As from a fire made of moist wood, various modifications of smoke proceed, so is the breathing of this great Being the Rig Veda, the Yajur Veda, the Sama Veda, the Atharvangirases, the Itihasas, Puranas, science, the Upanishads, verses (slokas), aphorisms, comment of different kinds are his breathings”.
In another place it says:
“Prajapati (identified with death or the devourer) is said to have produced Vach (speech) and through her, together with soul, to have created all things, including the Vedas”.
“By that speech and that soul he created all things whatsoever, rick, yajush, and saman texts, metres, sacrifices, creatures and animals.”
“The three Vedas are (identifiable with) these three things (speech, mind and breath). Speech is the Rig Veda, mind the Yajur Veda and breath the Sama Veda”.
IV
Coming to the Smritis, there are two theories as to the origin of the Vedas to be found in the Manu Smriti. In one place, it is said that the Vedas were created by Brahma:
“He (Brahma) in the beginning fashioned from the words of the Veda the several names, functions, and separate conditions of all (creatures). That Lord also created the subtle host of active and living deities, and of Sadhyas, an eternal sacrifice. And in order to the performance of sacrifice, he drew forth from Agni, from Vayu and from Surya, the triple eternal Veda, distinguished as Rick, Yajush and Saman.”
In another place, he seems to accept the story of Prajapati being the originator of the Vedas as would be evident from the following:
“Prajapati also milked out of the three Vedas, the letters, “a”, “u”, and “m” together with the words “bhu, “bhuvah” and “savar”. The same supreme Prajapati also milked from each of the three Vedas one of the three portions of the text called Savitri (or Gayatri), beginning with the word “tat…” The three great imperishable parties (bhuh, bhuavah, svar) preceded by Om, and the Gayatri of three lines, are to be regarded as the mouth of Brahma”.
V
It is also interesting to note what the Puranas have to say about the origin of the Vedas. The Vishnu Purana says:
“From his eastern mouth of Brahma formed the gayatra, the rick verses, the trivrit, the soma- rathyantara, and of sacrifices, the agnoshtoma. From his southern mouth he created the yajush verses, the trishtubh metre, the panchadasa-stoma, the vrihat-saman and the ukthya. From his western mouth he formed the saman verses, the jagatimetre, the saptadasa-stoma, the vairupa, and the atiratra. From his northern mouth he framed the ekavinsa, the atharvan, the aptoryaman, with the anushtubh and biraj metres”.
The Bhagvat Purana says:
“Once the Vedas sprang from the four-faced creator, as he was meditating how shall I create the aggregate worlds as before?… He formed from his eastern and other mouths the Vedas called rick, yajush, saman, and Atharvan, together with praise, sacrifice, hymns and expiation”. [There appears to be some quotations missing as there is no link between these two paragraphs].
“Entering between her eyes. From her there was then produced a quadruple being in the form of a male, lustrous as Brahma, undefined eternal, undecaying, devoid of bodily senses or qualities, distinguished by the attribute of brilliancy, pure as the rays of the moon, radiant, and embodied in letters. The god fashioned the Rig Veda, with the Yajush from his eyes, the Sama Veda from the tip of his tongue, and the Atharvan from his head. These Vedas, as soon as they are born, find a body (kshetra).

