Hayagrīva: Concerning remembering and forgetting, Bergson writes, "The cerebral mechanism is arranged just so as to drive back into the unconscious"—by unconscious they mean the subconscious—"almost the whole of his past, and to admit beyond the threshold only that which can cast light on the present situation or further the action now being prepared. In short, only that which can give useful work." So that, in other words, man utilizes only those memories or that knowledge which is immediately useful, and in this way man can function in the world. What is the role of Kṛṣṇa in this, as the arranger of this cerebral mechanism?
Prabhupāda: Cerebral mechanism, that is a machine. Just like this microphone is a machine. It helps speaking loudly. It has nothing..., machine has nothing to do with the voice, but it helps the voice louder so we can listen, so far the machine is concerned. Actually the voice is different. Therefore our Vedic śāstra is called voice, śruti. So if the śruti, the voice, vibration of this voice is proper, then the machine can help us to understand that. But if there is no voice, what is the use of the machine? Just like dead body: the same brain is there, what is the use? The same ear is there. So it is not the brain that helps; it is the voice, it is the instruction which helps. Therefore we take instruction of Kṛṣṇa. So that is the Kṛṣṇa's point. Kṛṣṇa says, yadā yadā hi dharmasya glānir bhavati (BG 4.7). When people becomes rascal, without any God consciousness, and the so-called demonic leaders keep the society in darkness, dharmasya glānir bhavati, at that time, to stop these demons talking nonsense, and to raise the devotees who are interested, Kṛṣṇa comes. That is Kṛṣṇa's coming. Then He leaves behind Him instruction of Bhagavad-gītā so that His devotees can preach for the benefit of the society. So it is not the brain; it is the voice, the instruction, which is important. So a human being has got this nice machine and he can take. But if the leaders are blind, they do not know what is the use of this brain, then it is useless.