Note [3:22:4:1]1. Agni purishya, i. e. the fire dwelling in the soil (comp. Roth in Kuhn's Zeitschrift, XXVI, 64), is mentioned very frequently in the Mantras belonging to the Agnikayana, i. e. to the construction of the brick altar. Agni is considered as residing in the soil used at that rite. Now in the Yagus texts the whole of our hymn occurs among the texts to be recited at the Agnikayana (Taitt. Samh. IV, 2, 4, 2, &c.; comp. also Asvalayana Srautasutra IV, 8, 20). Perhaps we may conjecture, therefore, that the Agnikayana rite in its simplest form was known already in the Rig-veda period, and that our hymn was destined for it.--The pravana fires (fires dwelling on the hill-sides) may be the fires dwelling in the rivers which run down the pravanas or descents.