Śatapatha Brāhmaṇa ("of a hundred paths") 1.1.3

He now prepares two strainers (pavitra), with the text (Vâg. S. I, 12 a): 'Purifiers (or strainers, pavitra) are ye, and belonging to Vishnu!' For Vishnu is the sacrifice; so that he thereby says, 'You belong to the sacrifice.'

Two there are of them: for means of cleansing (pavitra) is this (wind) which here ventilates (pavate); and this, it is true, ventilates as one only; but on entering into man, it becomes a forward and a backward one, and they are these two, to wit, the prâna (breathing out) and the udâna (breathing up or in). And as this (clarifying process) takes place in accordance with the measure of that (process of breathing), therefore there are two (strainers).

There may also be three: for the vyâna (or pervading vital air) is a third (kind of breathing); but in reality there are only two. Having then strained the sprinkling water with these two (strainers), he sprinkles with it. The reason why he strains it with the two (strainers) is this:

Vritra in truth lay covering all this (space) which here extends between heaven and earth, And because he lay covering (vri) all this, therefore his name is Vritra.

He strains it, with the text (Vâg. S. I, 12 b) 'By the impulse of Savitri I purify thee with this flawless purifier (or ventilator, pavitra), with the rays of the sun!' For Savitri is the impeller (prasavitri) of the gods, so that he strains this (water) as one impelled by Savitri. 'With this flawless purifier (ventilator, pavitra),' he says, because this (wind) which here ventilates (or purifies, pavate) is a flawless purifier. 'With the rays of the sun,' he says, because they, the rays of the sun, are certainly purifying; and for this reason he says, 'With the rays of the sun.'

Having taken it (the water with the ladle) in his left hand, he makes it spirt upwards with his right hand, and eulogises and glorifies it, with the text (Vâg. S. I, 12 c): 'Shining (or divine) waters! ye the first-going, the first-drinking ones!' For the waters are shining; and for this reason he says, 'Shining waters!' 'First-going,' he calls them, because they flow towards the sea and are therefore going in front (or forwards). 'First-drinking,' he calls them, because they are the first that drink of king Soma and are therefore 'drinking first.' And further: 'Forward now lead this sacrifice, forward the Lord of Sacrifice, the liberal, god-loving Lord of Sacrifice!' whereby he says, 'Well (lead) the sacrifice, well the sacrificer!'

And further (Vâg. S. I, 13 a): 'You Indra chose (for his companions) in the battle against Vritra!' For Indra, when he was battling with Vritra, did choose them (the waters) and with their help he killed him; and for this reason he says, 'You Indra chose in the battle against Vritra!'

'You chose Indra in the battle against Vritra!' for they, too, chose Indra when he was battling with Vritra, and with them he killed him: therefore he says, 'You chose Indra in the battle against Vritra!'

And further (Vâg. S. I, 13 d): 'Consecrated by sprinkling are ye!' With these words he makes amends to them. He then sprinkles the (first) oblation. One and the same meaning applies to the (whole process of) sprinkling, viz. he thereby makes sacrificially pure that (which he sprinkles).

He then sprinkles the sacrificial vessels, with the text (Vâg. S. I, 13 g), 'Be ye pure for the divine work, for the sacrifice to the gods!' for it is for the divine work, the sacrifice to the gods, that he consecrates them. 'Whatever, that belongs to you, the impure have defiled by touching, that I hereby purify for you!' For whatever belonging to them some impure one--either a carpenter or some other impure person--has on this occasion desecrated by touching, that he thereby renders sacrificially pure for them by means of the water; and therefore he says, 'Whatever, that belongs to you, the impure have defiled by touching, that I hereby purify for you!'