Dear all , the consecration sacrifice under the Soma sacrifice is the beginning of this brahmana. The process of consecration and its relevance is know to all. The word consecration means "making sacred". so the first step here essentially means purifying oneself for the yagna.
The 1-6 of Aitareya brahmana , deals with this process.
1. The Agni is the lowest of the gods and Vishnu the highest and all the gods exist between them. So we have to offer 11 potsherds of cake (rice) with 3 being for vishnu and remaining 8 for Agni. Eight symbolizes the metre gayathri which is the metre of Agni. In celestial presence , Agni and Vishnu are the terminal forms of the sacrifice. All deities are therefor equivalent to Vishnu and to Agni. A pap of Ghee is to be offered by those people who do not have any form of support on earth (which essentially means unmarried). The ghee is the from the milk of the woman (cow) and the rice grains the men which when paired gives propagation (either its as offspring, cattle , wealth ) of generation. This is the essential basis for grasping the yagna. Once this concept above is grasped, then the deities are grasped by one with the full moon and new moon sacrifices. this
full moon and new moon sacrifices are done as oblations with which one consecrate himself once. ( As per Acvalayana chrauta Sutra(ACS), the new and full moon sacrifices should precede the Agrayana , Nirunhapacu , the Chaturmasyas and soma sacrifice). Now the kindling verses of seventeen is recited ( 15 from Acvalayana chrauta Sutra (i.2.7)and 2 Dhayyas (iv.2.1) or the fifteen prescribed in Cankhayana Crauta Sutra (CCV) (v.3.3)) .Prajapathi is seventeen fold - 12 months , the season five with union of winter and cool
season. Thus its one year as taken as prajapathi as per time references.
