Maitrāyaṇīya Āraṇyaka 3.2.p1

3.2.p1

athā̍nya̱trāpyu̍kta̱m̐ yaḥ ka̱rtā so̱'yam̐ vai bhū̱tātmā̍ ka̱raṇai̍ḥ
kārayi̱tā'nta̍ḥpu̱ruṣo'tha̱ yathā̍'gni̍nā'yaṣpi̱ṇḍo vā̍'bhibhū̱taḥ
ka̱rtṛbhi̍rha̱nyamā̍no̱ nānātva̍mu̱paitye̍va̱m̐ vā̍va kha̱lvasau̍
bhū̱tātmā'nta̍ḥpu̱ruṣeṇā̍bhibhū̱to gu̱ṇairha̱nyamā̍no̱ nānātva̍mu̱paiti̱ catu̍rjālaṃ

And it is said elsewhere also: 'He who is the doer, this indeed is the elemental Self; he who causes action through the organs
is the inner Puruṣa. Now, just as a lump of iron overcome by fire
and beaten by blacksmiths assumes manifoldness, even so indeed that
elemental Self, overcome by the inner Puruṣa and beaten by the constituent qualities, assumes manifoldness. The fourfold net, divided fourteenfold, transformed into eighty-four [classes]—the multitude of beings—this indeed is the form of manifoldness. These indeed