The general argument of the common man is that since the Lord is not visible to our eyes, how can one surrender unto Him? To such a common man, here is a practical suggestion given by Śrīla Śukadeva Gosvāmī as to how one can perceive the Supreme Lord by reason and perception. One can perceive that intelligence is the form-direction of the Paramātmā plenary portion of the Personality of Godhead. Intelligence gives one direction like some higher authority, and the living being cannot see or move or eat or do anything without the use of intelligence. When one fails to take advantage of intelligence he becomes a deranged man, and so a living being is dependent on intelligence or the direction of a superior being. Such intelligence is all-pervading. Every living being has his intelligence, and this intelligence, being the direction of some higher authority, is just like a father giving direction to his son. The higher authority, who is present and residing within every individual living being, is the Superself.
The Bhagavad-gītā is the preliminary conception of the Personality of Godhead Śrī Kṛṣṇa, and Śrīmad-Bhāgavatam is the further explanation of the science of Godhead. So if we stick to our determination and pray for the mercy of the director of intelligence sitting within the same bodily tree, like a bird sitting with another bird (as explained in the Upaniṣads), certainly the purport of the revealed information in the Vedas becomes clear to our vision, and there is no difficulty in realizing the Supreme Personality of Godhead, Vāsudeva. The intelligent man therefore, after many births of such use of intelligence, surrenders himself at the lotus feet of Vāsudeva, as confirmed by the Bhagavad-gītā(7.19).
Ref >> Srila Prabhupada Vani.