Prabhupāda: Because Kṛṣṇa, as God, He demanded that sarva-dharmān parityajya mām ekaṁ śaraṇaṁ vraja (BG 18.66). But people misunderstood Him. Therefore Kṛṣṇa again came as guru and taught people how to surrender to Kṛṣṇa.
Śyāmasundara: Doesn't He say in the Bhagavad-gītā, "I am the spiritual master"?
Śyāmasundara: Doesn't Kṛṣṇa say "I am the spiritual master"? In Bhagavad-gītā it says...
Prabhupāda: Yes, He's the original spiritual master. Because He has accepted spiritual master of Arjuna. So what is the difficulty? Śiṣyas te 'haṁ śādhi māṁ tvāṁ prapannam (BG 2.7). "I am your disciple." So unless He's spiritual master, how Arjuna becomes His disciple? He's the original guru. Tene brahma hṛdā ādi-kavaye, in the Bhāgavata. That He gave instruction about Vedas in the heart of Brahmā. So He's guru.
Prabhupāda: Yes, He's the original guru. Then His disciple Brahmā is guru. Then his disciple Nārada is guru. Then his disciple Vyāsa is guru. In this way there is guru-paramparā. Evaṁ paramparā prāptam (BG 4.2), the transcendental knowledge is received through the disciplic succession.