Nitāi: Translation: "Before reciting this Śrīmad-Bhāgavatam, which is our very means of conquest, I offer my respectful obeisances unto the Personality of Godhead Nārāyaṇa, unto Nara-nārāyaṇa Ṛṣi, the supermost human being, unto mother Sarasvatī, the goddess of learning, and unto Śrīla Vyāsadeva, the author." (SB 1.2.4)
Prabhupāda: This is the paramparā system. As you get knowledge, step by step... Kṛṣṇa is the original spiritual master, and then from Kṛṣṇa, Lord Brahmā learned the Vedic knowledge. Tene brahma hṛdā ādi-kavaye (SB 1.1.1). In the Bhāgavata it is said that "Wherefrom Brahmā got his knowledge?" Because whenever we want to get knowledge, we must approach a superior person to get knowledge. Tad-vijñānārthaṁ sa gurum eva abhigacchet (MU 1.2.12). Guru means superior. So who was the superior person when Brahmā got knowledge? Because there was no other creature. He is the first creature. Therefore it is said, "The superior person was Kṛṣṇa, but He was not present." We see, Kṛṣṇa was present before Arjuna, but nobody was present before Brahmā. Therefore it is said, tene brahma hṛdā ādi-kavaye, hṛdā: "through the heart." Because Kṛṣṇa is situated in everyone's heart. Actually, He is the spiritual master, caitya-guru. So in order to help us, He comes out as physical spiritual master. And therefore sākṣād-dharitvena sama... Spiritual master is representative of Kṛṣṇa. Kṛṣṇa sends some sincere devotee to act on His behalf, and therefore he is spiritual master.