"Brahmaji received this science of Godhead from the Lord directly, and he handed over the same to Narada, who in his turn ordered Srila Vyasadeva to expand it. So the transcendental knowledge of the Supreme Lord is not mental speculation by the mundane wranglers, but is uncontaminated, eternal, perfect knowledge beyond the jurisdiction of material modes. The Bhagavata purana is therefore the direct incarnation of the Lord in the form of transcendental sound, and one should receive this transcendental knowledge from the bona fide representative of the Lord in the chain of disciplic succession from the Lord to Brahmaji, from Brahmaji to Narada, from Narada to Vyasa, from Vyasadeva to Sukadeva Gosvami, from Sukadeva Gosvami to Suta Gosvami. The ripened fruit of the Vedic tree drops from one hand to another without being broken by falling suddenly from a high branch down to the earth. Therefore unless one hears the science of Godhead from the bona fide representative of the disciplic succession, as above mentioned, for one to understand the theme of the science of Godhead will be a difficult job. It should never be heard from the professional Bhagavatam reciters who earn their livelihood by gratifying the senses of the audience."
Srimad-Bhagavatam 2:7:51 Purport
"Lord Brahma is the first living being, who directly learned the Vedic wisdom from the Lord (tene brahma hrda ya adi-kavaye). Therefore, who can be a more learned Vedantist than Lord Brahma? He admits that in spite of his perfect knowledge in the Vedas, he was unable to know the glories of the Lord. Since no one can be more than Lord Brahma, how can a so-called Vedantist be perfectly cognizant of the Absolute Truth? The so-called Vedantist, therefore, cannot enter into the existence of the Lord without being trained in the matter of bhakti-vedanta, or Vedanta plus bhakti. Vedanta means self-realization, and bhakti means realization of the Personality of Godhead, to some extent. No one can know the personality of Godhead in full, but at least to a certain extent one can know the Absolute Truth, the Personality of Godhead, by self-surrender and a devotional attitude, and by nothing else."
Srimad-Bhagavatam 2:6:33 Purport
"This age of Kali is not at all suitable for self-realization as was Satya-yuga, the golden age, or Treta- or Dvapara-yugas, the silver and copper ages. For self-realization, the people in Satya-yuga, living a lifetime of a hundred thousand years, were able to perform prolonged meditation. And in Treta-yuga, when the duration of life was ten thousand years, self-realization was attained by performance of great sacrifice. And in the Dvapara-yuga, when the duration of life was one thousand years, self-realization was attained by worship of the Lord. But in the Kali-yuga, the maximum duration of life being one hundred years only and that combined with various difficulties, the recommended process of self-realization is that of hearing and chanting of the holy name, fame, and pastimes of the Lord. The sages of Naimisaranya began this process in a place meant specifically for the devotees of the Lord. They prepared themselves to hear the pastimes of the Lord over a period of one thousand years. By the example of these sages one should learn that regular hearing and recitation of the Bhagavatam is the only way for self-realization. Other attempts are simply a waste of time, for they do not give any tangible results. Lord Sri Caitanya Mahaprabhu preached this system of Bhagavata-dharma, and He recommended that all those who were born in India should take the responsibility of broadcasting the messages of Lord Sri Krsna, primarily the message of Bhagavad-gita. And when one is well established in the teachings of Bhagavad-gita, he can take up the study of Srimad-Bhagavatam for further enlightenment in self-realization."
Srimad-Bhagavatam 1:1:21 Purport
Bhaktivedanta Book Trust. HDG A.C. Bhaktivedanta Swami Srila Prabhupada.