Śatapatha Brāhmaṇa ("of a hundred paths") 7.5.2.6

7.5.2.6

yadveva paśuśīrṣāṇyupadadhāti | prajāpatirvā idamagra āsīdeka eva so 'kāmayatānnaṃ sṛjeya prajāyeyeti sa prāṇebhya evādhi paśūnniramimīta manasaḥ puruṣa cakṣuṣo 'śvam prāṇādgāṃ śrotrādaviṃ vāco 'jaṃ tadyadenānprāṇebhyo 'dhi niramimīta tasmādāhuḥ prāṇāḥ paśava iti mano vai prāṇānām prathamaṃ tadyatmanasaḥ puruṣaṃ niramimīta tasmādāhuḥ puruṣaḥ prathamaḥ paśūnāṃ vīryavattama iti mano vai sarve ghrāṇā manasi hi sarve prāṇāḥ pratiṣṭhitāstadyanmanasaḥ puruṣaṃ niramimīta tasmādāhuḥ puruṣaḥ sarve paśava iti puruṣasya hyevaite sarve bhavanti

And, again, why he puts the heads of the victims thereon. Pragâpati alone was here at first. He desired, 'May I create food, may I be reproduced!' He fashioned animals from his vital airs, a man from his soul (mind), a horse from his eye, a cow from his breath, a sheep from his ear, and a goat from his voice; and inasmuch as he created them from the vital airs, people say that 'Animals are vital airs.' The soul is the first of the vital airs; and inasmuch as he fashioned man from his soul, they say that 'Man is the first, and strongest of animals.' The soul is all the vital airs, for in the soul all the vital airs are established. And inasmuch as he fashioned man from his soul, they say that 'Man is all animals,' for they all belong to man.