MUṆḌAKA UPANISHAD · 2.2.2

यदर्चिमद्यदणुभ्योऽणु च
यस्मिँल्लोका निहिता लोकिनश्च ।
तदेतदक्षरं ब्रह्म स प्राणस्तदु वाङ्मनः
तदेतत्सत्यं तदमृतं तद्वेद्धव्यं सोम्य विद्धि ॥ २॥

yadarcimadyadaṇubhyo’ṇu ca
yasmim̐llokā nihitā lokinaśca ।
tadetadakṣaraṃ brahma sa prāṇastadu vāṅmanaḥ
tadetatsatyaṃ tadamṛtaṃ tadveddhavyaṃ somya viddhi ॥ 2॥

That which is the Luminous, that which is smaller than the atoms, that in which are set the worlds and their peoples, That is This, — it is Brahman immutable: life is That, it is speech and mind. That is This, the True and Real, it is That which is immortal: it is into That that thou must pierce, O fair son, into That penetrate.

Sri Aurobindo · CWSA 18, p. 139