Śatapatha Brāhmaṇa ("of a hundred paths") 8.1.1

He lays down the Prânabhritah (breath-holders): now, the Prânabhritah being--the vital airs, it is the vital airs he thereby bestows upon (Agni). He lays them down in the first layer;--that which is the first layer is the forepart (ground-part) of Agni: it is thus in front that he puts (into Agni) the vital airs, whence there are (in creatures) these (orifices of the) vital airs in front.

He lays them down by ten and ten, for there are ten vital airs; and even though 'ten-ten' may mean many, times, here they mean only ten. Five times he puts on ten (bricks) each time; for it is those five (kinds of sacrificial) animals he bestows, and there are ten vital airs in each.animal: upon all of them he thus bestows the vital airs. He lays down (the bricks) so as not to be separated from the animals: he thus bestows vital airs not separated from the animals. He lays them down on every side: on every side he thus bestows on them (orifices of) the vital airs.

And again why he lays down the Prânabhritah. From Pragâpati, when relaxed (by producing creatures), the vital airs departed. To them, having become deities, he spake, 'Come ye to me, return ye unto me that wherewith ye have gone out of me!'--'Well then, create thou that food which we will await here looking on!'--'Well then, let us both create!'--'So be it!'--So both the final airs and Pragâpati created that food, these Prânabhrit (bricks).

In front (of the altar) he lays down (ten bricks,--the first) with (Vâg. S. XIII, 54), 'This one in front, the Existent,'--in front, doubtless, is Agni; and as to why he speaks of him (as being) 'in front,' it is because they take out the fire (from the Gârhapatya) towards the front, and attend on Agni towards the front. And as to why he says 'the existent (bhuva),' Agni is indeed the existent, for it is through Agni that everything exists (bhû) here. Agni, indeed, having become the breath, remained in front: it is that very form he now bestows (on Agni).

[The others with], 'His, the Existent's son, the Breath,'--from out of that form, fire, he (Pragâpati) fashioned the breath;--'Spring, the son of the breath,'--from out of the breath he fashioned the spring-season;--'The Gâyatrî, the daughter of the Spring,'--from out of the spring-season he fashioned the Gâyatrî metre;--'From the Gâyatrî the Gâyatra,'--from out of the Gâyatrî metre he fashioned the Gâyatra hymn-tune;--'From the Gâyatra the Upâmsu,'--from out of the Gâyatra hymn-tune he fashioned the Upâmsu-graha;-- 'From the Upâmsu the Trivrit,'--from out of the Upâmsu-graha he fashioned the nine-versed hymn-form;--'From the Trivrit the Rathantara,'--from out of the Trivrit-stoma he fashioned the Rathantara-prishtha.

'The Rishi Vasishtha,'--the Rishi Vasishtha, doubtless, is the breath: inasmuch as it is the chief (thing) therefore it is Vasishtha (the most excellent); or inasmuch as it abides (with living beings) as the best abider (vastri), therefore also it is Vasishtha.--'By thee, taken by Pragâpati,'--that is, 'by thee, created by Pragâpati,'--'I take breath for my descendants (and people)!'--therewith he introduced the breath from the front. Separately he lays down (these ten bricks): what separate desires there are in the breath, those he thereby lays into it. Only once he settles them: he thereby makes it one breath; but were he to settle them each separately, he assuredly would cut the' breath asunder. This brick is trivrit (threefold): the formula, the settling, and the sûdadohas, that is threefold, and threefold is Agni,--as great as Agni is, as great as is his measure, so much he lays down (on the altar) by so dying.

And on the right (south) side with (Vâg. S. XIII, 55), 'This one on the right, the all-worker,'--the all-worker (visvakarman), doubtless, is this Vâyu (the wind) who blows here, for it is he that makes everything here; and because he speaks of him as (being) 'on the right,' therefore it is in the south that he blows most. Vâyu, indeed, having become the mind, remained in the right side (of the body): it is that form (part) he now bestows (on Agni).

'His, the all-worker's child, the Mind,'--from out of that (all-working) form, the wind, he fashioned the mind;--'the summer, the son of the mind,'--from out of the mind he fashioned the summer season;--'the Trishtubh, the daughter of Summer,'--from out of the summer season he fashioned the Trishtubh metre;--'from the Trishtubh the Svâra tune,'--from out of the Trishtubh metre he created the Svâra hymn-tune;--'from the Svâra the Antaryâma,'--from out of the Svâra-sâman he fashioned the Antaryâma-graha;--'from the Antaryâma the Pañkadasa,'--from out of the Antaryâma-cup he fashioned the fifteen-versed hymn-form;--'from the Pañkadasa the Brihat,'--from out of the Pañkadasa-stoma he fashioned the Brihat-prishtha.

'The Rishi Bharadvâga,'--the Rishi Bharadvâga, doubtless, is the mind;--'vâga' means 'food,' and he who possesses a mind, possesses (bharati) food, 'vâga;' therefore the Rishi Bharadvâga is the mind.--'By thee, taken by Pragâpati,'--that is, 'by thee, created by Pragâpati;'--'I take the mind for my descendants!'--therewith he introduced the mind from the right side. Separately he lays down (these ten bricks): what separate desires there are in the mind, those he thereby lays into it. Only once he settles them: he thereby makes it one mind; but were he to settle them each separately, he assuredly would cut asunder the mind. This brick is threefold: the meaning of this has been explained.