45. (The agni built of mind, &c.) is a particular form of the preceding one (i.e. the agni built of bricks), on account of the leading subject-matter; it is (part of) the act; as in the case of the mânasa cup.
Your supposition, the pûrvapakshin objects, as to those fire-altars being not supplementary to the sacrificial act,
The case is analogous to that of the 'mental' (cup). On the tenth day of the Soma sacrifices occupying twelve days--which day is termed avivâkya--a soma cup is offered mentally, the earth being viewed as the cup, the sea as the Soma and Pragâpati as the divinity to which the offering is made. All rites connected with that cup, viz. taking it up, putting it down in its place, offering the liquid in it, taking up the remaining liquid, the priests inviting one another to drink the remainder, and the drinking, all these rites the text declares to be mental only, i.e. to be done in thought only 2. Yet this mental quasi-cup, as standing under the heading of a sacrificial act, forms part of that act.--The same then holds good with regard to the quasi-agnis made of mind and so on.
261:1 I.e. of the agni made of bricks which is the outcome of the agnikayana.--Ân. Gi. explains vikalpavisesha by prakârabheda.
261:2 2 Cp. Tândya Brâh. IV, 9; Taitt. Samh. VII, 3, 1.
