Srimad-Bhagavatam: Canto 7 - Chapter 1 - Verse 25
बुद्धेर्जागरणं स्वप्न: सुषुप्तिरिति वृत्तय: ।ता येनैवानुभूयन्ते सोऽध्यक्ष: पुरुष: पर: ॥ २५ ॥
buddher jāgaraṇaṁ svapnaḥsuṣuptir iti vṛttayaḥtā yenaivānubhūyanteso ’dhyakṣaḥ puruṣaḥ paraḥ
Intelligence can be perceived in three states of activity — wakefulness, dreaming and deep sleep. The person who perceives these three is to be considered the original master, the ruler, the Supreme Personality of Godhead.
Without intelligence one cannot understand the direct activities of the senses, nor can he understand dreaming or the cessation of all gross and subtle activities. The seer and controller is the Supreme Personality of Godhead, the Supreme Soul, by whose direction the individual soul can understand when he is awake, when he is sleeping, and when he is completely in trance. In Bhagavad-gītā (15.15) the Lord says, sarvasya cāhaṁ hṛdi sanniviṣṭo mattaḥ smṛtir jñānam apohanaṁ ca: “I am seated in everyone’s heart, and from Me come remembrance, knowledge and forgetfulness.” The living entities are completely absorbed in the three states of wakefulness, dreaming and deep sleep through their intelligence. This intelligence is supplied by the Supreme Personality of Godhead, who accompanies the individual soul as a friend. Śrīla Madhvācārya says that the living entity is sometimes described as sattva-buddhi when his intelligence acts directly to perceive pains and pleasures above activities. There is a dreaming state in which understanding comes from the Supreme Personality of Godhead (mattaḥ smṛtir jñānam apohanaṁ ca). The Supreme Personality of Godhead, the Supersoul, is the supreme controller, and under His direction the living entities are subcontrollers. One must understand the Supreme Personality of Godhead with one’s intelligence.