CC Ādi 17.257
supaṭhita vidyā kārao nā haya prakāśa
When all the students thus resolved, criticizing Śrī Caitanya Mahāprabhu, their intelligence was spoiled. Thus although they were learned scholars, because of this offense the essence of knowledge was not manifested in them.
In the Bhagavad-gītā it is said, māyayāpahṛta-jñānā āsuraṁ bhāvam āśritāḥ: when one becomes inimical to the Supreme Personnality of Godhead, adopting an atheistic attitude (āsuraṁ bhāvam), even if one is a learned scholar the essence of knowledge does not become manifested in him; in other words, the essence of his knowledge is stolen by the illusory energy of the Lord. In this connection Śrī Bhaktisiddhānta Sarasvatī Ṭhākura quotes a mantra from the Śvetāśvatara Upaniṣad (6.23):
tasyaite kathitā hy arthāḥ prakāśante mahātmanaḥ
The purport of this verse is that one who is unflinchingly devoted to the Supreme Personality of Godhead, Viṣṇu, 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 manifested. This essence is nothing but surrender unto the Supreme Personality of Godhead (vedaiś ca sarvair aham eva vedyaḥ). Only unto one who fully surrenders to the spiritual master and the Supreme Lord does the essence of Vedic knowledge become manifested, not to anyone else. This same principle is emphasized by Śrī Prahlāda Mahārāja in Śrīmad-Bhāgavatam (7.5.24):
kriyate bhagavaty addhā tan manye ’dhītam uttamam
“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 literatures very well, for the goal of studying the Vedic literature is to understand the supremacy of Lord Śrī Kṛṣṇa.” Śrīdhara Svāmī 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 Mahārāja Khaṭvāṅga 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 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. Śrīmad-Bhāgavatam (Bhāg. 11.11.18) declares:
śramas tasya śrama-phalo hy adhenum iva rakṣataḥ
“If one is learned in the Vedic literature but is not a devotee of Lord Viṣṇu, his work is a useless waste of labor, just like the keeping of a cow that does not give milk.”
Anyone who does not follow the surrendering process but is simply interested in an academic career cannot make any advancement. His profit is only his labor for nothing. If one is expert in the study of the Vedas but does not surrender to a spiritual master or Viṣṇu, all his cultivation of knowledge is but a waste of time and labor.