In the Bhagavad-gita it is said, mayayapahrta-jnana asuram bhavam asritah: when one becomes inimical to the Supreme Personality of Godhead, adopting an atheistic attitude (asuram bhavam), even if one is a learned scholar the essence of knowledge does not become manifest in him; in other words, the essence of his knowledge is stolen by the illusory energy of the Lord. In this connection Sri Bhaktisiddhanta Sarasvati Thakura quotes a mantra from the Svetasvatara Upanisad (6.23):

The purport of this verse is that one who is unflinchingly devoted to the Supreme Personality of Godhead, Visnu, and similarly devoted to the spiritual master, with no ulterior motive, becomes a master of all knowledge. In the heart of such a devotee, the real essence of the Vedic knowledge becomes manifest. This essence is nothing but surrender unto the Supreme Personality of Godhead (vedais ca sarvair aham eva vedyah). Only unto one who fully surrenders to the spiritual master and the Supreme Lord does the essence of Vedic knowledge become manifest, not to anyone else. This same principle is emphasized by Sri Prahlada Maharaja in Srimad-Bhagavatam (7.5.24):

"A person who directly applies these nine principles [hearing, chanting, remembering, etc.] in the service of the Lord is to be understood as a greatly learned man who has assimilated the Vedic literature very well, for the goal of studying the Vedic literature is to understand the supremacy of Lord Sri Krsna." Sridhara Svami confirms in his commentary that first one must surrender to the spiritual master; then the process of devotional service will develop. It is not a fact that only one who diligently pursues an academic career can become a devotee. Even with no academic career, if one has full faith in the spiritual master and the Supreme Personality of Godhead, he develops in spiritual life and real knowledge of the Vedas. The example of Maharaja Khatvanga confirms this. One who surrenders is understood to have learned the subject matter of the Vedas very nicely. One who adopts this Vedic process of surrender learns devotional service and is certainly successful. One who is very much proud, however, is unable to surrender either to the spiritual master or to the Supreme Personality of Godhead. Thus he cannot understand the essence of any Vedic literature. Srimad-Bhagavatam (Bhag. 11.11.18) declares:

"If one is learned in Vedic literature but is not a devotee of Lord Visnu, his work is a useless waste of labor, just like the keeping of a cow that does not give milk."