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. Before worshiping the Lord . . . just like here Kṛṣṇa said in the beginning ācāryopāsanam, and in the middle he says, mayi cānanya-yogena bhaktir avyabhicāriṇī. So before engaging yourself in devotional service to the Lord, you must first of all worship ācārya, ācāryopāsanam.
One cannot become a devotee personally. Just like some rascals say: "What is the use of accepting guru?" Of course, they have got very bad experience. But who is ācārya? Ācārya means one who has received the Vedic knowledge through the paramparā system. Evaṁ paramparā-prāptam imaṁ rājarṣayo viduḥ (BG 4.2). He is ācārya. Ācārya cannot be manufactured, self-made. No. He must come down from the disciplic succession. He is ācārya. You have to approach such ācārya who is coming in disciplic succession. Ācāryavan puruṣo veda. One who is under the shelter of ācārya, he knows things. So Kṛṣṇa recommends also here that if you actually want to become in knowledge, if you want to have real knowledge, then you must worship ācārya. Ācāryopāsanam. This is Vedic system. Tad vijñānārthaṁ sa gurum evābhigacchet (MU 1.2.12).
It is not that, "If I like, I can go to a guru; if I don't like, I can learn the books at home and learn everything." No, that is not possible. Practically . . . just like if you purchase some medical book and study at home, and if you begin to practice, you will be called a quack. You will not be recognized by the government. You will not get the practitioner's registration. You will not. Unless you have passed through the medical college, your medical examination, you will not be accepted, even if you say that, "I have read all the books." Similarly, if you simply think that, "I have read . . ." As we see generally, "Oh, I have read Bhagavad-gītā hundred times." But you ask him what is Kṛṣṇa, he cannot say. Because he has not approached the ācārya. This is the difficulty. He may . . . he might have read Bhagavad-gītā a thousand times, but he will not understand a single word, because he has not approached.