One has to understand actually what is Kṛṣṇa in complete. If you want to that, know that, then this is the process, mayi, mayi āsakta-manaḥ, mayy āsakta-manaḥ (BG 7.1), the mind has to be engaged in Kṛṣṇa, first thing is. Mind. Therefore, Kṛṣṇa manifests Himself in this Deity form. The Deity is Kṛṣṇa Himself. But we cannot concentrate Kṛṣṇa which is not visible. Kṛṣṇa is not visible to the ordinary eyes. Ataḥ śrī-kṛṣṇa na bhaved grāhyam indriyaiḥ (CC Madhya 17.136). God is not perceptible with our this material eyes, our material senses. Ataḥ śrī-kṛṣṇa-nāmādi na . . . even material ears. You are chanting. If you are not spiritually advanced, this chanting of Hare Kṛṣṇa mantra also will not appeal. It will be happening mechanically. But by chanting you will gradually advance, ceto-darpaṇa-mārjanam, then you will understand that this Hare Kṛṣṇa mantra is not different from Kṛṣṇa. The mantra, the sound vibration, is also Kṛṣṇa.
So we have to, I mean to say, repose our mind to the form of Kṛṣṇa. Kṛṣṇa says mayi, "Unto Me, Kṛṣṇa." We cannot see now Kṛṣṇa personally. Personally He is here, but we want to see anything physically. Physically He is also there. Here, Kṛṣṇa mūrti is physical, but because you are differently educated, you do not know what is this world of physics. We think that this is different from Kṛṣṇa. That will be explained. Therefore it is said, tac chṛṇu. Asaṁśayaṁ samagraṁ māṁ yathā jñāsyasi tac chṛṇu. "You just hear from Me, as you can understand Me in complete, without any doubt." So Kṛṣṇa is instructing Himself, about Himself. So why there should be any doubt? There cannot be any doubt. God is explaining Himself about Him, then why there should be doubt? This is the . . . this is called bhakti-yoga. Mad-āśrayaḥ. Mayy āsakta-manāḥ pārtha.