One should be qualified enough to discern transcendental potency, and either by discriminating or by fortunate chance if one is able to receive the transcendental sound from the bona fide spiritual master, his path of liberation is guaranteed
SB Canto 2
Lord Brahmā underwent penances for one thousand years by the calculations of the demigods. He heard this transcendental vibration from the sky, and he accepted it as divine. Thus he controlled his mind and senses, and the penances he executed were a great lesson for the living entities. Thus he is known as the greatest of all ascetics.
Lord Brahmā heard the occult sound tapa, but he did not see the person who vibrated the sound. And still he accepted the instruction as beneficial for him, and therefore he engaged himself in meditation for one thousand celestial years. One celestial year is equal to 6 x 30 x 12 x 1000 of our years. His acceptance of the sound was due to his pure vision of the absolute nature of the Lord. And due to his correct vision, he made no distinction between the Lord and the Lord's instruction. There is no difference between the Lord and sound vibration coming from Him, even though He is not personally present. The best way of understanding is to accept such divine instruction, and Brahmā, the prime spiritual master of everyone, is the living example of this process of receiving transcendental knowledge. The potency of transcendental sound is never minimized because the vibrator is apparently absent. Therefore Śrīmad-Bhāgavatam or Bhagavad-gītā or any revealed scripture in the world is never to be accepted as an ordinary mundane sound without transcendental potency.
One has to receive the transcendental sound from the right source, accept it as a reality and prosecute the direction without hesitation. The secret of success is to receive the sound from the right source of a bona fide spiritual master. Mundane manufactured sound has no potency, and as such, seemingly transcendental sound received from an unauthorized person also has no potency. One should be qualified enough to discern such transcendental potency, and either by discriminating or by fortunate chance if one is able to receive the transcendental sound from the bona fide spiritual master, his path of liberation is guaranteed. The disciple, however, must be ready to execute the order of the bona fide spiritual master as Lord Brahmā executed the instruction of his spiritual master, the Lord Himself. Following the order of the bona fide spiritual master is the only duty of the disciple, and this completely faithful execution of the order of the bona fide spiritual master is the secret of success.
Lord Brahmā controlled his two grades of senses by means of sense perception and sense organs because he had to engage such senses in the execution of the order of the Lord. Therefore controlling the senses means engaging them in the transcendental service of the Lord. The Lord's order descends in disciplic succession through the bona fide spiritual master, and thus execution of the order of the bona fide spiritual master is factual control of the senses. Such execution of penance in full faith and sincerity made Brahmājī so powerful that he became the creator of the universe. And because he was able to attain such power, he is called the best amongst all the tapasvīs.