Shatapatha Brahmana 13.6.1.11

13.6.1.11

athādhyātmam pratiṣthaivāsya prathamamahaḥ pratiṣṭho asya vasanta ṛturyadūrdhvam pratiṣṭhāyā avācīnam maddhyāttaddvitīyamahastadvasya grīṣma ṛturmadhyamevāsya madhyamamaharmadhyamasya varṣāśaradāvṛtū yadūrdhvam madhyādavācīnam śīrṣṇastaccaturthamahastadvasya hemanta ṛtuḥ śira evāsya pañcamamahaḥ śiro'sya śiśira ṛturevamime ca lokā samvatsaraścātmā ca puruṣamedhamabhisampadyante sarvam vā ime lokāḥ sarvaṃ samvatsaraḥ sarvamātmā sarvam puruṣamedhaḥ sarvasyāptyai sarvasyāvaruddhyai

Then as to the body. The first day is its feet, and the spring season also is its feet; and the second day is what is above the feet, and below the waist, and the summer season also is that (part) of it; and the central day is its waist, and the rainy and autumn seasons also are its waist; the fourth day is what is above the waist and below the head, and the winter season also is that (part) of it; and the fifth day is its head, and the dewy season also is its head:--thus these worlds, as well as the year and the (sacrificer's) self, pass into the Purushamedha for the obtainment and securing of everything, for, indeed, these worlds are everything, and the year is everything, and the self is everything, and the Purushamedha is everything.