Maitri (Maitrāyaṇīya) Upaniṣad 6.1

6.1

atha prapāṭhaka 6 |
dvidhā vā eṣa ātmānaṃ bibhartyayaṃ yaḥ prāṇo yaścāsā ādityo'tha dvau vā etā asya panthānā antarbahiścāhorātreṇaitau vyāvartete asau vā ādityo bahirātmāntarātmā prāṇo'to bahirātmakyā gatyāntarātmano'numīyate gatirityevaṃ hi āhātha yaḥ kaścidvidvānapahatapāpmā'kṣādhyakṣo'vadātamanāstanniṣṭha āvṛttacakṣuḥ so antarātmakyā gatyā bahirātmano'numīyate gatirityevaṃ ha āha atha ya eṣo'ntarāditye hiraṇmayaḥ puruṣo yaḥ paśyatīmāṃ hiraṇyavasthāt sa eṣo'ntare hṛtpuṣkara evāśrito'nnamatti ||

1. He [i. e. the Soul, Ātman] bears himself (ātmānam) twofold: as the breathing spirit (prāṇa) here, and as yon sun (āditya).

Likewise, two in number, verily, are these his paths : an inner and an outer. Both these return upon themselves with a day and a night.

Yon sun, verily, is the outer Soul (Ātman). The inner Soul (Ātman) is the breathing spirit.

Hence the course of the inner Soul (Ātman) is measured by the course of the outer Soul (Ātman). For thus has it been said: ‘Now, whoever is a knower, freed from evil, an overseer of his senses, pure-minded, established on That, introspective, is even He [i. e. the Soul, the Ātman].’

And the course of the outer Soul (bahir-ātman) is measured by the course of the inner Soul (antar-ātman). For thus has it been said: ‘Now, that golden Person who is within the sun, who looks down upon this earth from his golden place, is even He who dwells within the lotus of the heart and eats food.’