Text 21
Knowledge of the Absolute Sense is a knowledge of the sense of the Absolute Sense.
363
Supreme Personality of Godhead, the Absolute Truth, is described in the Second Chapter of the First Canto as follows:
śṛṇvatāṁ sva-kathāṁ kṛṣṇaḥ puṇya-śravaṇa-kīrtanaḥ hrdyantahstho hy abhadrāni vidhunoti suhrt satām.
naşṭa-prāyeṣv abhadreṣu nityaṁ bhāgavata-sevayā bhagavaty uttama-śloke bhaktir bhavati naiṣṭhikī.
tadā rajas-tamo-bhāvāḥ kāma-lobhādayaś ca ye ceta etair anāviddhaṁ sthitaṁ sattve prasīdati.
evam prasanna-manaso bhagavad-bhakti-yogataḥ bhagavat-tattva-vijñānaṁ mukta-saṅgasya jāyate.
bhidyate hṛdaya-granthiś chidyante sarva-saṁśayāḥ kṣīyante cāsya karmāṇi dṛṣṭa evātmanīśvare.
“To hear about Kṛṣṇa from Vedic literatures, or to hear from Him directly through the  Bhagavad-gītā , is itself righteous activity. And for one who hears about Kṛṣṇa, Lord Kṛṣṇa, who is dwelling in everyone’s heart, acts as a best-wishing friend and purifies the devotee who constantly engages in hearing of Him. In this way, a devotee naturally develops his dormant transcendental knowledge. As he hears more about Kṛṣṇa from the  Bhāgavatam  and from the devotees, he becomes fixed in the devotional service of the Lord. By development of devotional service one becomes freed from the modes of passion and ignorance, and thus material lusts and avarice are diminished. When these impurities are wiped away, the candidate remains steady in his position of pure goodness, becomes enlivened by devotional service and understands the science of God perfectly. Thus  bhakti-yoga  severs the hard knot of material affection and enables one to come at once to the stage of ‘ asaṁśayaṁ samagram ,’ understanding of the Supreme Absolute Truth Personality of Godhead.” ( Bhāg.  1.2.17-21)
Therefore only by hearing from Kṛṣṇa or from His devotee in Kṛṣṇa consciousness can one understand the science of Kṛṣṇa.
TEXT 2
ज्ञानं तेऽहं सविज्ञानमिदं वक्ष्याम्यशेषतः । यज्ज्ञात्वा नेह भूयोऽन्यज्ज्ञातव्यमवशिष्यते ॥ २ ॥