Below is a very nice conversation with Srila Prabhupada where devotees ask him many different questions to explain some of the verses in Bhagavad-gita. For example, what is it like in terms of perception when your senses are purified, how do you take on different bodies life after life, do you feel pain not as much when in sattva guna, do we have outer and inner senses, what does it really mean to speculate? Etc.
Harikeśa: Śrīla Prabhupāda, what's the difference between a Brahmavādī and a Māyāvādī?

Prabhupāda: That you already questioned. We answered.

Harikeśa: I did?

Prabhupāda: Yes. [break] …vādī means those who are aspiring to merge into the impersonal Brahman effulgence.

Harikeśa: And Māyāvādīs, they do not attain that impersonal realization?

Prabhupāda: Māyāvādīs remain fools forever.

Harikeśa: They never leave this material platform.

Prabhupāda: They do not know. They have no knowledge. Aviśuddha-buddhayaḥ [SB 10.2.32], always impure. Otherwise how they are thinking, so ‘ham: “I am same. I am God. I am moving the sun, I am…” Such rascals, they remain always in ignorance. [break] …no sense that “If I am the same, then why I have fallen down in this māyā?” They say, “It is my līlā. I have become dog. So it is my līlā. I have become hog. It is my līlā.” (laughs) This is their philosophy. Hare Kṛṣṇa. [break] Māyāvāda. They are fools, mūḍha. Māyayāpahṛta-jñānā. They are described in the Bhagavad-gītā. Māyāvādī means māyayāpahṛta-jñānā: "Their knowledge has been taken away by māyā." Fools. Either you call them fool or call them lowest of the mankind or the most sinful, whatever way you can call, they are like that. All good qualifications. Therefore Caitanya Mahāprabhu has warned, māyāvādī-bhāṣya śunile haya sarva-nāśa: [Cc. Madhya 6.169] "If you hear from Māyāvādī, then your spiritual life is finished." It's so dangerous.

Harikeśa: The Brahmavādīs have some possibility of advancement?

Prabhupāda: Oh, yes.

Harikeśa: What is that thing that enables them to advance?

Prabhupāda: That you will know later on. First of all try to understand this. Don't try to understand everything in a moment. That is foolishness. [break] That argument is clear?

Ambarīṣa: Yes.

Prabhupāda: No, no. Spirit soul is changing machine. That is explained in the Bhagavad-gītā. So when this machine is finished, and another machine.

Ambarīṣa: The old machine continues to change after the spirit soul leaves, it deteriorates? The old machine deterior…, it breaks down.

Prabhupāda: Yes, yes. You give up one machine and you take another machine. [break]

Devotee (1): …one goes into a subtle machine?

Prabhupāda: That example is given, vāsāṁsi jīrṇāni yathā vihāya [Bg. 2.22]. Just like your dress, when it is useless, you throw it away and take another dress. It is stated in the Bhagavad-gītā. Vāsāṁsi jīrṇāni yathā vihāya gṛhṇāti naraḥ aparāṇi. You accept another set of dress. Clearly explained. [break] …also very scientific. Just like according to your last life's desires, you have got this dress, this body. So it is going on, going on, going on. Now you are creating another set of desires in this life. So you require a different dress. Then you begin another satisfaction of your desires. This is going on. Karmāṇa daiva-netreṇa: [SB 3.31.1] by your karma, you are creating a situation. Just like the criminal, he has created a situation; he cannot live anymore outside the jail. "Come on, here." He will go in automatically. So they do not know how nature is working. It is clearly said, prakṛteḥ kriyamāṇāni [Bg. 3.27]. "Nature is working, and that nature is working," mayādhyakṣeṇa [Bg. 9.10], "under My superintendence." Everything is there. Mayādhyakṣeṇa prakṛtiḥ sūyate sa-carācaram. Jagat, it is changing, always changing. How it is changing? Under the direction of God. Mayādhyakṣeṇa.

Devotee (1): Only Kṛṣṇa is doing everything then.

Prabhupāda: Yes. Kṛṣṇa is not like you that when you are given some business, you become embarrassed. That is the difference between Kṛṣṇa and you. He never becomes embarrassed.

Devotee (1): Śrīla Prabhupāda, is it true that our advancement in devotional services… Is it influenced a lot by our past karma, how many sinful activities we have committed?

Prabhupāda: No, no, no. Bhakti is not under karma. Bhakti is under your good will. If you accept to surrender to Kṛṣṇa, you can do that without being checked by anything else. Simply you have to will, "Yes, Kṛṣṇa. You are asking me. So long I did not do. From this day I do." That will depend upon you.

Devotee (2): Not that if I was more sinful, I would make less advancement than somebody who is more pious.

Prabhupāda: Whatever you may be, simply surrender and everything is finished. Ahaṁ tvāṁ sarva-pāpebhyo mokṣayiṣ… [Bg. 18.66]. Even if you are sinful, Kṛṣṇa will give you release, “All right. You have surrendered. That’s all right.” That is wanted. If you reserve something and cheat Kṛṣṇa, “Now I am surrendering,” Kṛṣṇa is very intelligent. “You have still reservation. No.” [break]

Devotee (1): …it's easier to surrender to Kṛṣṇa.

Prabhupāda: Yes, in sattva-guṇa one can see, one can understand his position. [break]

Devotee (2): Does he experience the miseries of the gross body when he's in sattva-guṇa, in the mode of goodness? Does he experience hunger and thirst, those things like that?

Prabhupāda: Gross body means no hunger?

Devotee (2): When a person's in sattva-guṇa, he's not so much feeling the pain…

Prabhupāda: He is not disturbed by the rajo-guṇa, tamo-guṇa. That is sattva-guṇa. Naṣṭa-prayeṣv abhadreṣu [SB 1.2.18]. He can be disturbed by rajo-guṇa, tamo-guṇa, but when he is in sattva-guṇa, he is not so much disturbed. And if he increase and go to the pure sattva-guṇa, suddha-sattva, then he is no more disturbed. At that time he can understand what is God. [break] …you are strongly situated in sattva-guṇa, the other base qualities cannot disturb you. Tadā rajas-tamo-bhāvāḥ kāma-lobhādayaś ca ye [SB 1.2.19]. Other guṇa means lusty desires and greediness. This thing will be finished when you are strongly situated in sattva-guṇa. Then you go advance more and more. [break] …hear about Kṛṣṇa, to chant about Kṛṣṇa, means cleansing, cleansing the dirty things of rajo-guṇa and tamo-guṇa. [break] …world is going on on rajo-guṇa and tamo-guṇa. Very minute quantity of population are by sattva-guṇa.

Brahmānanda: Perhaps only in India will you find people in…

Prabhupāda: Yes, some. That is also deteriorating. [break] The sattva-guṇa… the Māyāvādī, they are also supposed to be in sattva-guṇa, but mixed with rajo-guṇa, tamo-guṇa. Therefore not pure.

Devotee (2): You were saying that when one is in the mode of goodness, that he is on the mental platform?

Prabhupāda: Hmm?

Devotee (2): Does that mean that he's not… He's experiencing the subtle body inside of the gross body, or what does that mean exactly?

Prabhupāda: Mental platform is mixed sattva-guṇa, rajo-guṇa, not pure. But if you keep always Kṛṣṇa in your mind, then you are purified. The mind has no other opportunity to keep anything else. Kṛṣṇa is sitting there, then guarantee. [break] …they keep always seeing Viṣṇu form within the heart. Therefore they keep in sattva-guṇa. Similarly, if you keep Kṛṣṇa, then you are in sattva-guṇa. And when that concentration on Kṛṣṇa is not disturbed, then it is śuddha-sattva. That is spiritual platform. [break] …ekādaśī?

Nitāi: It's Saturday, the 6th.

Devotee (2): What does the yogi perceive when he cuts off the outer senses, he finally reaches the…

Prabhupāda: Perceive?

Devotee (2): What does he experience when he cuts off the outer senses and is able to…

Prabhupāda: Outer senses, what do you mean by outer senses-dead?

Devotee (2): His bodily senses.

Prabhupāda: There is no question of outer senses. Senses purified. What do you mean by outer senses?

Devotee (2): The senses with which you perceive the outer gross…

Prabhupāda: That always remains. But when it is not purified, you perceive material things. When it is purified, you perceive spiritual things.

Devotee (2): So the same gross senses will be able to see spiritual things.

Prabhupāda: Yes, it is purified. Bhakti is the purifying process. I have already said. Not that the eyes are suffering from cataract disease, "Pluck out." That is Māyāvādī philosophy.

Devotee (2): What does that mean, then, when the yogis withdraw their senses from the objects like it says like the tortoise withdraws his limbs within the shell? What does that refer to then?

Prabhupāda: Hm? What is that? I do not follow.

Brahmānanda: He asks, in the yoga system…

Prabhupāda: Yoga system means always see Supersoul; that is real yoga system. Perfection. Dhyānāvasthita-tad-gatena manasā paśyanti yaṁ yoginaḥ [SB 12.13.1]. Yoginaḥ, being meditating and seeing the Supersoul, this is yoga. Not that he does not see. He is seeing Supersoul. He is seeing nothing else.

Devotee (1): He doesn't see the Supersoul with the gross senses, though, does he?

Prabhupāda: Pure senses. He does not… Impure senses and pure senses.

Devotee (2): How can you tell when your senses are getting purified?

Prabhupāda: You will understand Kṛṣṇa more and more. So long your senses are not purified, you will not understand clearly what is Kṛṣṇa. [break] …understanding Kṛṣṇa means detestful to the material world, attached to Kṛṣṇa. Bhaktiḥ pareśānubhavaḥ viraktir anyatra syāt. [break]

Devotee (2): Is it true that eventually by this process we'll become purified so we can become like śruti-dharas?

Prabhupāda: That you will see when you become purified.

Devotee (2): Then we will actually attain that condition, then.

Prabhupāda: Try to become purified. Don't imagine and guess, "What will be the condition when I am purified?" This is all nonsense. Try to become purified.

Devotee (2): Then you perceive it.

Prabhupāda: Yes.

Brahmānanda: You tell the story of the potter. He has many pots. (Prabhupāda laughs) And he tries to imagine what it will be like when he becomes very wealthy.

Prabhupāda: That is nonsense, waste time. [break] …you are eating you will understand yourself, “Yes, I am eating, I am getting strength, I am getting satisfaction.” But simply theory…, “What will happen after eating? What will happen?” You eat and you see what is happening. What is the use of asking this question? You eat and you will understand. [break]

Brahmānanda: …Harrison, he wrote in his preface that "The proof of the pudding is in the eating."

Prabhupāda: Yes.