Knowledge means not this material knowledge. Actual knowledge is to advance in spiritual knowledge. Just in this Bhagavad-gītā the beginning of knowledge was instructed by Kṛṣṇa that, "I am not this body." Dehino 'smin yathā dehe kaumāraṁ yauvanaṁ jarā (BG 2.13). "I am encaged in this body. I am not this body." Unfortunately, at the present moment, this is accepted knowledge, bodily concept, "I am . . ." "I am Indian," "I am American," "I am brāhmaṇa," "I am kṣatriya." This is going on. Actually the knowledge begins when one understands, "I am not American," "I am not Indian," "I am not brāhmaṇa," "I am not kṣatriya." Then what you are? Caitanya Mahāprabhu says, gopī-bhartuḥ pada-kamalayor dāsa-dāsānu-dāsa (CC Madhya 13.80): "I am the servant of the servant of the servant of Kṛṣṇa, the provider of the gopīs," gopī-bhartuḥ. That is my real identification. Not this body.
So to understand this knowledge one has to approach ācārya. Ācārya means one who knows the purpose of Vedic literature, śāstra, āśṛṇoti yaḥ śāstram, and practices and teaches his disciple. He knows. Ācārya means knows. One who knows the purpose of Vedic literature, he practices in his life, and he teaches his disciple, he is called ācārya. So ācārya upāsanam.