As long as one is absorbed in the bodily conception, his activities are performed on that platform. This is not very difficult to understand. In the world, we see that every nation is trying to supersede every other nation and that every man is trying to advance beyond his fellow man. All these activities are going on under the name of advancement of civilization. There are many plans for making the body comfortable, and these plans are carried in the subtle body after the destruction of the gross body. It is not a fact that after the gross body is destroyed the living entity is finished. Although many great philosophers and teachers in this world are under the impression that after the body is finished everything is finished, this is not a fact. Nārada Muni says in this verse that at death one takes his plans with him (gṛhṇīyāt), and to execute these plans he gets another body. This is called punar bhavaḥ. When thegross body is finished, the plans of the living entity are taken by the mind, and by the grace of the Lord, the living entity gets a chance to give these plans shape in the next life. This is known as the law of karma. As long as the mind is absorbed in the laws of karma, a certain type of body must be accepted in the next life.
(Srimad Bhagavatam----4:29:62----purport).

There is an English proverb that says, "The face is the index of the mind." If one is angry, his anger is immediately expressed in his face. Similarly, other mental states are reflected by the actions of the gross body. In other words, the activities of the gross body are reactions of the mental condition. The mind's activities are thinking, feeling and willing. The willing portion of the mind is manifest by the activities of the body. The conclusion is that by the activities of the body and senses, we can understand the condition of the mind. The condition of the mind is affected by past activities in the past body. When the mind is joined with a particular sense, it immediately becomes manifest in a certain way.
(Srimad Bhagavatam----4:29:63----purport).

The activities of the living entity in the body of a dog may be experienced in the mind of a different body; therefore those activities appear never to have been heard or seen. The mind continues, although the body changes. Even in this life-span we can sometimes experience dreams of our childhood. Although such incidents now appear strange, it is to be understood that they are recorded in the mind. Because of this, they become visible in dreams. The transmigration of the soul is caused by the subtle body, which is the storehouse of all kinds of material desires. Unless one is fully absorbed in Kṛṣṇa consciousness, material desires will come and go. That is the nature of the mind—thinking, feeling and willing. As long as the mind is not engaged in meditation on the lotus feet of the Supreme Personality of Godhead, Kṛṣṇa, the mind will desire so many material enjoyments. Sensual images are recorded in the mind in chronological order, and they become manifest one after another; therefore the living entity has to accept one body after another. The mind plans material enjoyment, and the gross body serves as the instrument to realize such desires and plans. The mind is the platform onto which all desires come and go.
(Srimad Bhagavatam----4:29:68----purport).

The desires in the subtle body of mind, intelligence and ego cannot be fulfilled without a gross body composed of the material elements earth, water, air, fire and ether. When the gross material body is not manifest, the living entity cannot factually act in the modes of material nature. In this verse it is clearly explained that the subtle activities of the mind and intelligence continue due to the sufferings and enjoyments of the living entity's subtle body. The consciousness of material identification (such as "I" and "mine") still continues because such consciousness has been extant from time immemorial. However, when one transfers to the spiritual world by virtue of understanding Kṛṣṇa consciousness, the actions and reactions of both gross and subtle bodies no longer bother the spirit soul.
(Srimad Bhagavatam----4:29:70----purport).

Foolish people deny the existence of the soul, but it is a fact that when we sleep we forget the identity of the material body and when we awake we forget the identity of the subtle body. In other words, while sleeping we forget the activities of the gross body, and when active in the gross body we forget the activities of sleeping. Actually both states—sleeping and waking—are creations of the illusory energy. The living entity actually has no connection with either the activities of sleep or the activities of the so-called wakened state. When a person is in deep sleep or when he has fainted, he forgets his gross body. Similarly, under chloroform or some other anesthetic, the living entity forgets his gross body and does not feel pain or pleasure during a surgical operation. Similarly, when a man is suddenly shocked by some great loss, he forgets his identification with the gross body. At the time of death, when the temperature of the body rises to 107 degrees, the living entity falls into a coma and is unable to identify his gross body. In such cases, the life air that moves within the body is choked up, and the living entity forgets his identification with the gross body. Because of our ignorance of the spiritual body, of which we have no experience, we do not know of the activities of the spiritual body, and in ignorance we jump from one false platform to another. We act sometimes in relation to the gross body and sometimes in relation to the subtle body. If, by Kṛṣṇa's grace, we act in our spiritual body, we can transcend both the gross and subtle bodies. In other words, we can gradually train ourselves to act in terms of the spiritual body.
(Srimad Bhagavatam----4:29:71----purport).

When a living entity is within the womb, his gross body, the ten sense organs and the mind are not fully developed. At such a time the objects of the senses do not disturb him. In a dream a young man may experience the presence of a young woman because at that time the senses are active. Because of undeveloped senses, a child or boy will not see a young woman in his dreams. The senses are active in youth even when one dreams, and although there may be no young woman present, the senses may act and there may be a seminal discharge (nocturnal emission). The activities of the subtle and gross bodies depend on how developed conditions are. The example of the moon is very appropriate. On a dark-moon night, the full shining moon is still present, but it appears not to be present due to conditions. Similarly, the senses of the living entity are there, but they only become active when the gross body and the subtle body are developed. Unless the senses of the gross body are developed, they will not act on the subtle body. Similarly, because of the absence of desires in the subtle body, there may be no development in the gross body.
(Srimad Bhagavatam----4:29:72----purport).

It is sometimes said that because a child is innocent he is completely pure. Actually this is not the fact. The effects of fruitive activities reserved in the subtle body appear in three concurrent stages. One is called bīja (the root), another is called kūṭa-stha (the desire), and another is called phalonmukha (about to fructify). The manifest stage is called prārabdha (already in action). In a conscious or unconscious state, the actions of the subtle or gross bodies may not be manifest, but such states cannot be called the liberated state. A child may be innocent, but this does not mean that he is a liberated soul. Everything is held in reservation, and everything will become manifest in due course of time. Even in the absence of certain manifestations in the subtle body, the objects of sense enjoyment may act. The example has been given of a nocturnal emission, in which the physical senses act even when the physical objects are not manifest. The three modes of material nature may not be manifest in the subtle body, but the contamination of the three modes remains conserved, and in due course of time, it becomes manifest. Even if the reactions of the subtle and gross bodies are not manifest, one does not become free from the material conditions. Therefore it is wrong to say that a child is as good as a liberated soul.
(Srimad Bhagavatam----4:29:73----purport).

"The living entities in this conditioned world are My eternal, fragmental parts. Due to conditioned life, they are struggling very hard with the six senses, which include the mind."
Here it is also explained that the living entity comes in contact with the sixteen material elements and is influenced by the three modes of material nature. The living entity and this combination of elements combine to form what is called jīva-bhūta, the conditioned soul that struggles hard within material nature. The total material existence is first agitated by the three modes of material nature, and these become the living conditions of the living entity. Thus the subtle and gross bodies develop, and the ingredients are earth, water, fire, air, sky, and so on. According to Śrī Madhvācārya, when consciousness, the living force in the heart, is agitated by the three modes of material nature, then the subtle body of the living entity, consisting of the mind, the sense objects, the five senses that acquire knowledge and the five senses for acting in the material condition, becomes possible.
(Srimad Bhagavatam----4:29:74----purport).

Material nature is very strong, and the material modes force one to accept another body. This force is visible when the living entity transmigrates from a superior body to an inferior one. One who acts like a dog or hog in the present body will certainly be forced to accept the body of a dog or hog in the next life. A person may be enjoying the body of a prime minister or a president, but when he understands that he will be forced to accept the body of a dog or hog, he chooses not to leave the present body. Therefore he lies in a coma many days before death. This has been experienced by many politicians at the time of death. The conclusion is that the next body is already determined by superior control. The living entity immediately gives up the present body and enters another. Sometimes in the present body the living entity feels that many of his desires and imaginations are not fulfilled. Those who are overly attracted to their life situation are forced to remain in a ghostly body and are not allowed to accept another gross body. Even in the body of a ghost, they create disturbances for neighbors and relatives. The mind is the prime cause of such a situation. According to one's mind, different types of bodies are generated, and one is forced to accept them.
(Srimad Bhagavatam----4:29:76-77----purport).

Then a person, even though a caṇḍāla, is initiated by a pure devotee into chanting the holy name of the Lord, his body changes as he follows the instructions of the spiritual master. Although one cannot see how his body has changed, we must accept, on the grounds of the authoritative statements of the śāstras, that he changes his body. This is to be understood without arguments. This verse clearly says, sa jahāti bandham: "He gives up his material bondage." The body is a symbolic representation of material bondage according to one's karma. Although sometimes we cannot see the gross body changing, chanting the holy name of the Supreme Lord immediately changes the subtle body, and because the subtle body changes, the living entity is immediately freed from material bondage. After all, changes of the gross body are conducted by the subtle body. After the destruction of the gross body, the subtle body takes the living entity from his present gross body to another. In the subtle body, the mind is predominant, and therefore if one's mind is always absorbed in remembering the activities or the lotus feet of the Lord, he is to be understood to have already changed his present body and become purified. Therefore it is irrefutable that a caṇḍāla, or any fallen or lowborn person, can become a brāhmaṇa simply by the method of bona fide initiation.
(Srimad Bhagavatam----5:1:35----purport).