Śatapatha Brāhmaṇa ("of a hundred paths") 10.5.2.8

10.5.2.8

sa eṣa etasminmaṇḍale puruṣo'thaitadamṛtaṃ yadetadarcirdīpyate tasmānmṛtyurna mriyate'mṛte hyantastasmādu na dṛśyate'mṛte hyantaḥ

The Lokamprinâ (space-filling brick) is the same as that (gold man in the sun): it is that (brick) which this entire Agni finally results in. Moreover, this man (or person) in the left eye is the mate of that one (in the right eye and in the sun); and a mate is one half of one's own self, for when one is with a mate he is whole and complete: thus it (the second man) is for the sake of completeness. And as to there being two of these (persons in the eyes), a pair means a productive couple: hence two Lokamprinâs are laid down each time, and hence they set up the layer by two (kinds of bricks).