parokṣaṁ mama ca priyam
In the previous verses Lord Kṛṣṇa clearly refuted the concept that Vedic knowledge is meant for material enjoyment, and here the Lord summarizes the actual purpose of Vedic literature: self-realization. Although the conditioned souls are struggling in the network of material energy, their actual existence is transcendental freedom in the kingdom of God. The Vedas gradually lift the conditioned soul out of the darkness of illusion and establish him in the eternal loving service of the Lord. As stated in the Vedānta-sūtra (4.4.22), anāvṛttiḥ śabdāt: “One who properly hears Vedic knowledge does not have to return to the cycle of birth and death.”
One may ask why the Lord Himself as well as the Lord’s representatives, the Vedic seers and mantras, speak in esoteric or indirect terms. As the Lord states in Bhagavad-gītā, nāhaṁ prakāśaḥ sarvasya: the Supreme Lord does not allow Himself to be taken cheaply, and thus He is not manifest to superficial or inimical people. Those who are polluted by the material atmosphere are induced to purify themselves through Vedic rituals that offer fruitive results, just as a child is induced to take medicine by the offer of a candy reward. Because of the confidential nature of Vedic exposition, less intelligent persons cannot appreciate the ultimate transcendental purpose of the Vedas, and consequently they fall down to the platform of sense gratification.
The term brahmātma (“spirit soul”) ultimately indicates the Supreme Personality of Godhead, who states in Bhagavad-gītā that knowledge of Him is rāja-guhyam, the most confidential of all secrets. One who depends upon material sense perception remains in gross ignorance of the Absolute Truth. One who depends upon mental and intellectual speculation may get a clue that the eternal soul and Supersoul are both within the material body. But one who depends upon the Lord Himself, faithfully hearing the Lord’s own message in Bhagavad-gītā, perfectly understands the entire situation and goes back home, back to Godhead, having fulfilled the true purpose of Vedic knowledge.