Maitri (Maitrāyaṇīya) Upaniṣad 3.3

3.3

athānyatrāpyuktaṃ yaḥ kartā so'yaṃ vai bhūtātmā karaṇaiḥ kārayitāntaḥpuruṣo'tha yathāgnināyaḥpiṇḍo vābhibhūtaḥ kartṛbhirhanyamāno nānātvamupaityevaṃ vāva khalvasau bhūtātmāntaḥpuruṣeṇābhibhūto guṇairhanyamāno nānātvamupaityatha yattriguṇaṃ caturaśītilakṣayonipariṇataṃ bhūtatriguṇametadvai nānātvasya rūpaṃ tāni ha vā imāni guṇāni puruṣeṇeritāni cakramiva cakriṇetyatha yathāyaḥpiṇḍe hanyamāne nāgnirabhibhūyatyevaṃ nābhibhūyatyasau puruṣo'bhibhūyatyayaṃ bhūtātmopasaṃśliṣṭatvāditi ||

3. “Now, it has elsewhere been said: ‘Verily, he who is the doer is the elemental soul. The causer of action through the organs is the inner Person. Now, verily, as a lump of iron, overcome by fire and beaten by workmen, passes over into a different form—so, assuredly, indeed, the elemental soul,

overcome by the inner Person and beaten by Qualities, passes over into a different form. The mode of that different form, verily, has a fourfold covering, is fourteenfold, is transformed in eighty-four different ways, is a host of beings. These varieties, verily, are driven by the Person, like "the wheel by the potter." Now, as, when a lump of iron is being hammered, the fire [in it] is not overcome, so that Person is not overcome. This elemental soul (_bhūtātman_) is overcome (_abhibhūta_) because of its attachment [to Qualities].'