Bob: The guru should be accepted as representative of God?
Prabhupāda: Yes, guru is representative. Guru is the external manifestation of Kṛṣṇa.
Bob: But different than . . . like the incarnations of Kṛṣṇa that come?
Prabhupāda: Yes.
Bob: In what way is the external manifestation of the guru different than the external manifestation of, let us say, Kṛṣṇa or Caitanya when They come to earth.
Prabhupāda: Guru is one, representative of Kṛṣṇa. So there are symptoms who is guru. The general symptoms are described in the Vedas: tad-vijñānārthaṁ gurum evābhigacchet, śrotriyaṁ brahma-niṣṭham (MU 1.2.12). The first symptom is śrotriyam. Guru is in disciplic succession: one who has thoroughly heard about the Vedas through his spiritual master. This is general description. So another description is in the Bhāgavatam:
- tasmād guruṁ prapadyeta
- jijñāsuḥ śreya uttamam
- śabde pare ca niṣṇātaṁ
- brahmaṇy upaśamāśrayam
- (SB 11.3.21)
Generally, the guru's symptom is that he's a perfect devotee. That's all. And he's serving Kṛṣṇa by preaching His message.