YV 6.7h

The theologians say, 'Mitra appropriates the well-performed part of the sacrifice, Varuna the ill-performed; where then is the sacrifice, and where the sacrificer?; In that he offers a cow to Mitra and Varuna, by Mitra [3] he propitiates the well- performed part of the sacrifice, by Varuna the ill-performed; the sacrificer is not ruined. Even as men plough the field with the plough, so do the Rc and the Saman plough the sacrifice; in that he offers a cow to Mitra and Varuna, verily he rolls a roller over the ploughed-up sacrifice, for atonement. The metres of him who has sacrificed are worn out, the cow is the sap of the metres; in that he offers the cow to Mitra and Varuna, he again delights the metres, to drive away weariness; verily also he bestows sap upon the metres. The gods divided up power and strength; what there was left over became the Atigrahya cups, and that is why the Atigrahyas have their name. In that the Atigrahyas are drawn, verily thus the sacrificer bestows. upon himself power and strength, brilliance by that for Agni, power by that for Indra, splendour by that for Surya. The Atigrahyas are the support of the sacrifice, the Prsthas are the two wheels, if he were not to. draw them in the Prsthya (rite), the Prsthas would destroy the sacrifice in front; if he were to draw them in the Ukthya [1], the Atigrahyas would destroy the sacrifice behind; but they should be drawn in the Viçvajit with all the Prsthas, so that the sacrifice may have all its strength. Prajapati indicated the sacrifices to the gods, he put away their dear forms, they became the Atigrahya; 'Bodiless is his sacrifice', they say, 'for whom the Atigrahyas are not drawn.' They should be drawn also in the Agnistoma, so that the sacrifice may have its body.