Shatapatha Brahmana 8.4.2.15

8.4.2.15

tadyadete atropadadhāti | saṃvatsara eṣo 'gnirima u lokāḥ saṃvatsarastasya yadūrdhvamantarikṣādarvācīnaṃ divastadasyaiṣā caturthī citistadvasya hemanta ṛtustadyadete atropadadhāti yadevāsyaite ātmanastadasminnetatpratidadhāti tasmādete atropadadhāti

And as to why he places these two (bricks) in this (layer),--this Agni (fire-altar) is the year, and the year is these worlds: what part thereof is above the air, and below the sky, that is this fourth layer, and that is the winter-season thereof; and when he places these two in this (layer), he thereby restores to him (Pragâpati-Agni, the year and fire-altar) what part of his body these two (constitute). This is why he places these two in this (layer).