We are part and parcel of Kṛṣṇa. Kṛṣṇa is sac-cid-ānanda vigraha (Bs. 5.1). His transcendental body is eternal, blissful and complete knowledge, His body. Therefore He's speaking Bhagavad-gītā. If He's an ordinary man, what is the use of hearing Him? Ordinary man will commit mistake, will cheat, will be illusioned. His senses are imperfect. How he can give complete knowledge? That is not possible. Therefore we are not concerned to hear any rascal. We want to hear Kṛṣṇa. We are not prepared to hear any rascal, so-called scientists and so-called philosopher, so-called God. No. We are not prepared. Because everyone is rascal. Everyone is full of mistakes, everyone is trying to cheat others, everyone is illusioned and everyone's senses are imperfect. How he can give knowledge, perfect? That is not possible.
Therefore, we have to select guru. Guru means Kṛṣṇa. As Arjuna has selected guru, śiṣyas te 'haṁ śādhi māṁ tvāṁ prapannam (BG 2.7): "I am . . . I become Your śiṣya, disciple, and I surrender unto You," so to get perfect knowledge, we have to find out Kṛṣṇa or Kṛṣṇa's bona fide representative. Then there is perfect knowledge. Then we can become immortal. Unless we get perfect knowledge, that is no . . . so Kṛṣṇa is sac-cid-ānanda-vigrahaḥ (Bs. 5.1), immortal. Kṛṣṇa is full of bliss, full of knowledge, and we are also part and parcel of Kṛṣṇa, so we have also the same quality, sac-cid-ānanda, the spiritual body.