Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 20

Sanskrit:

विज्ञानमेतत्‍त्रियवस्थमङ्गगुणत्रयं कारणकार्यकर्तृ ।समन्वयेन व्यतिरेकतश्चयेनैव तुर्येण तदेव सत्यम् ॥ २० ॥

ITRANS:

vijñānam etat triy-avastham aṅgaguṇa-trayaṁ kāraṇa-kārya-kartṛsamanvayena vyatirekataś cayenaiva turyeṇa tad eva satyam

Translation:

The material mind manifests in three phases of consciousness — wakefulness, sleep and deep sleep — which are products of the three modes of nature. The mind further appears in three different roles — the perceiver, the perceived and the regulator of perception. Thus the mind is manifested variously throughout these threefold designations. But it is the fourth factor, existing separately from all this, that alone constitutes the Absolute Truth.

Purport:

As stated in Kaṭha Upaniṣad (2.2.15), tam eva bhāntam anubhāti sarvaṁ/ tasya bhāsā sarvam idaṁ vibhāti: “Everything radiates its illumination in pursuance of His original illumination; His light illuminates everything in this universe.” As thus described, the entire range of perception, cognition and sensitivity is an insignificant expansion of the perception, cognition and sensitivity of the Personality of Godhead.