Aitareyabrahmana 4.13

4.13

The two sāmans are the Bṛhat and the Rathaṃtara.
The Bṛhat and the Rathaṃtara are the two ferry-boats of the sacrifice;
by means of them they cross over the year.
The Bṛhat and the Rathaṃtara are the two feet; this day is the head.
By means of the two feet they approach splendour, the head.
The Bṛhat and the Rathaṃtara are the two wings; this day is the head.
By means of the two wings they reach out to splendour, the head.
Those two are not to be let go together.
If they should let both go together,
just as a boat severed from its mooring floats about, reaching shore after shore,
so would those sacrificial session performers float about, reaching shore after shore,
who should let both go together.
Then, if they let go the Rathaṃtara, through the Bṛhat both are not let go;
and if they let go the Bṛhat, through the Rathaṃtara both are not let go.
What is the Rathaṃtara, that is the Vairūpa; what is the Bṛhat, that is the Vairāja.
What is the Rathaṃtara, that is the Śākvara; what is the Bṛhat, that is the Raivata.
Thus these two are not let go.
Those who, knowing thus, undertake this day,
having attained the year day by day, having attained [it] half-month by half-month, having attained [it] month by month,
having attained the stomas and the metres, having attained all the deities, performing ascetic heat,
consuming their share of soma, pressing [soma] throughout the year, they sit.
Those who undertake the year upwards from this point,
they place a heavy burden upon themselves; a heavy burden crushes [them].
Now, he who undertakes it from below, having attained it from beyond by ritual actions,
he reaches the further shore of the year in safety.