Kanda I, adhyaya 2, brahmana 3
THE PREPARATION OF THE ALTAR
5. Thereupon the gods ordained this to be the dakṣiṇā at the new- and full-moon sacrifices, to wit, the Anvāhārya mess of rice , 'lest the oblation should be without a dakṣiṇā.' That (rinsing water) he pours out (for each Āptya) separately: thus he avoids a quarrel among them. He makes it hot (previously) : thus it becomes boiled (drinkable) for them. He pours it out with the formulas, 'For Trita thee!' 'For Dvita thee!' 'For Ekata thee!'--Now it is as an animal sacrifice that this sacrificial cake is offered .
8. When it (the rice-cake) still consists of rice-meal, it is the hair . When he pours water on it, it becomes skin . When he mixes it, it becomes flesh: for then it becomes consistent; and consistent also is the flesh. When it is baked, it becomes bone: for then it becomes somewhat hard; and hard is the bone. And when he is about to take it off (the fire) and sprinkles it with butter, he changes it into marrow. This is the completeness which they call 'the fivefold animal sacrifice.'
FOOTNOTES AND REFERENCES:
 That is to say, the sacrificial cake is a substitute or symbol (pratimā) for the animal sacrifice (as this it would seem was originally a substitute for the human sacrifice) by which the sacrificer redeems himself from the gods. Cf. Śat. Br. XI, 1, 8, 3; Taitt. Br. III, 2, 8, 8. The initiation (dīkṣā) of the sacrificer constitutes his consecration as the victim at the animal sacrifice (Śat. Br. XI, 7, 1, 3; Ait. Br. II, 3; 9; 11; Taitt. Br. II, 2, 82; T. S. VI, 1, 11, 6; Kaush. Br. X, 3; XI, 8), or as the sacrificial food at the haviryajña (Śat. Br. III, 3, 4, 21; Taitt, Br. III, 2, 8, 9), or as the horse at the horse-sacrifice (Taitt. Br. III, 9, 17, 4-5), &c. See, also, Taitt. S. VII, 2, 30, 4; Kāṭh. 34, 11, where it is said that one must p. 50 not perform the dvādaśāha for any one, since in having to eat of the victim, the cake, &c., one would eat the sacrificer's own flesh, &c. Cf. Weber, Ind. Streifen, I, p. 73. In accordance with these notions it would seem that man originally sacrificed his equal, as the best substitute for his own self; and that, as advancing civilisation rendered human sacrifices distasteful, the human victim was supplied by domestic animals, ennobled by constant contact with man; and finally by various materials of human diet.
 According to Sāyaṇa, because, like the hair of the victim, the particles of the ground rice are minute and numerous. According to Ait. Br. II, 9, on the other hand, the awn or beard of the rice represents the hair; the husks the skin; the minute particles of chaff removed by the final winnowings, the blood; the ground rice the flesh; and 'whatever other substantial part is in the rice' are the bones of the victim.