Aitareyabrahmana 4.28

4.28

bṛhac ca vā idam agre rathaṃtaraṃ cāstāṃ.
vāk ca vai tan manaś cāstāṃ, vāg vai rathaṃtaram mano bṛhat.
tad bṛhat pūrvaṃ sasṛjānaṃ rathaṃtaram atyamanyata.
tad rathaṃtaraṃ garbham adhatta, tad vairūpam asṛjata
te dve bhūtvā rathaṃtaraṃ ca vairūpaṃ ca bṛhad atyamanyetāṃ.
tad bṛhad garbham adhatta, tad vairājam asṛjata
te dve bhūtvā bṛhac ca vairājaṃ ca rathaṃtaraṃ ca vairūpam cātyamanyetāṃ.
tad rathaṃtaraṃ garbham adhatta, tac chākvaram asṛjata
tāni trīṇi bhūtva rathaṃtaraṃ ca vairūpam ca śākvaraṃ ca bṛhac ca
vairājaṃ cātyamanyanta.
tad bṛhad garbham adhatta, tad raivatam asṛjata
tāni trīṇy anyāni trīṇy anyāni ṣaṭ pṛṣṭhāny āsaṃs
tāni ha tarhi trīṇi chandāṃsi ṣaṭ pṛṣṭhāni nodāpnuvan.
sā gāyatrī garbham adhatta, sānuṣṭubham asṛjata.
triṣṭub garbham adhatta, sā pa/nktim asṛjata.
jagatī garbham adhatta, sātichandasam asṛjata.
tāni trīṇy anyāni trīṇy anyāni ṣaṭ chandāṃsy āsan ṣaṭ pṛṣṭhāni.
tāni tathākalpanta, kalpate yajño 'pi
tasyai janatāyai kalpate yatraivam etāṃ chandasāṃ ca pṛṣṭhānāṃ ca
kḷptiṃ vidvān dīkṣate dīkṣate

iv. 28 (xix. 6). In the beginning there were here the Bṛhat and the Rathantara; they were speech and mind; the Rathantara speech, the Bṛhat mind; the Bṛhat as first born despised the Rathantara; the Rathantara conceived and produced the Vairūpa; having become two, the Rathantara and the Vairūpa, they despised the Bṛhat. Then the Bṛhat conceived and produced the Vairāja; having become two, the Bṛhat and the Vairāja, they despised the Rathantara and the Vairūpa. Then the Rathantara conceived and produced the Çākvara; these having become three, the Rathantara and the Vairūpa and the Çākvara, despised the Bṛhat and the Vairāja. The Bṛhat conceived and produced the Raivata. These three and those three were the Pṛṣṭhas. The three metres were not enough for six Pṛṣṭhas. The Gāyatrī conceived and produced the Anuṣṭubh; the Triṣṭubh conceived and produced the Paṅkti; the Jagatī conceived and produced the Atichandas. These three and those three others were the six metres; the Pṛṣṭhas were six; thus they came into order. The sacrifice is in order; (all) is in order for that folk where one knowing thus this ordering of the metres and the Pṛṣṭhas consecrates himself.