MUṆḌAKA UPANISHAD · 3.1.9

एषोऽणुरात्मा चेतसा वेदितव्यो
यस्मिन्प्राणः पञ्चधा संविवेश ।
प्राणैश्चित्तं सर्वमोतं प्रजानां
यस्मिन्विशुद्धे विभवत्येष आत्मा ॥ ९॥

eṣo’ṇurātmā cetasā veditavyo
yasminprāṇaḥ pañcadhā saṃviveśa ।
prāṇaiścittaṃ sarvamotaṃ prajānāṃ
yasminviśuddhe vibhavatyeṣa ātmā ॥ 9॥

This Self is subtle and has to be known by a thought-mind into which the life-force has made its fivefold entry: all the conscious heart of creatures is shot through and inwoven with the currents of the life-force and only when it is purified can this Self manifest its power.

Sri Aurobindo · CWSA 18, pp. 143, 144