The difference between self-realization and material illusion is to know that the temporary or illusory impositions of material energy in the shape of gross and subtle bodies are superficial coverings of the self. The coverings take place due to ignorance. Such coverings are never effective in the person of the Personality of Godhead. Knowing this convincingly is called liberation, or seeing the Absolute. This means that perfect self-realization is made possible by adoption of godly or spiritual life. Self-realization means becoming indifferent to the needs of the gross and subtle bodies and becoming serious about the activities of the self. The impetus for activities is generated from the self, but such activities become illusory due to ignorance of the real position of the self. By ignorance, self-interest is calculated in terms of the gross and subtle bodies, and therefore a whole set of activities is spoiled, life after life. When, however, one meets the self by proper culture, the activities of the self begin. Therefore a man who is engaged in the activities of the self is called jīvan-mukta, or a liberated person even in the conditional existence.
(Srimad Bhagavatam----1:3:33----purport).

Since the gross and subtle bodies are emanations from the Personality of Godhead, the knowledge of light permits one to engage both of them in the service of the Lord. The gross body should be engaged in acts of rendering service to the Lord (as in bringing water, cleansing the temple or making obeisances, etc.). The path of arcanā, or worshiping the Lord in the temple, involves engaging one's gross body in the service of the Lord. Similarly, the subtle mind should be engaged in hearing the transcendental pastimes of the Lord, thinking about them, chanting His name, etc. All such activities are transcendental.
(Srimad Bhagavatam----1:5:27----purport).

This service attitude will induce the great souls to be more favorable in bestowing their mercy, which injects the neophyte with all the transcendental qualities of the pure devotees. Gradually this is developed into a strong attachment to hearing the transcendental pastimes of the Lord, which makes him able to catch up the constitutional position of the gross and subtle bodies and beyond them the knowledge of pure soul and his eternal relation with the Supreme Soul, the Personality of Godhead. After the relation is ascertained by establishment of the eternal relation, pure devotional service to the Lord begins gradually developing into perfect knowledge of the Personality of Godhead beyond the purview of impersonal Brahman and localized Paramātmā. By such puruṣottama-yoga, as it is stated in the Bhagavad-gītā, one is made perfect even during the present corporeal existence, and one exhibits all the good qualities of the Lord to the highest percentage. Such is the gradual development by association of pure devotees.
(Srimad Bhagavatam----1:5:34----purport).

The water of the Causal Ocean is differently situated than the covering water of the universe. The water that serves as covering for the universe is material, whereas the water of the Causal Ocean is spiritual. As such, the watery covering mentioned herein is considered to be the false egoistic covering of all living entities, and the gradual process of liberation from the material coverings, one after another, as mentioned herein, is the gradual process of being liberated from false egoistic conceptions of the material gross body, and then being absorbed in the identification of the subtle body till the attainment of the pure spiritual body in the absolute realm of the kingdom of God.
(Srimad Bhagavatam----2:2:28----purport).

The whole Vedic philosophy of life is that one should get rid of the material encagement of gross and subtle bodies, which only cause one to continue in a condemned life of miseries. This material body continues as long as one is not detached from the false conception of lording it over material nature. The impetus for lording it over material nature is the sense of "mine" and "I." "I am the lord of all that I survey. So many things I possess, and I shall possess more and more. Who can be richer than I in wealth and education? I am the master, and I am God. Who else is there but me?" All these ideas reflect the philosophy of ahaṁ mama, the conception that "I am everything." Persons conducted by such a conception of life can never get liberation from material bondage.
(Srimad Bhagavatam----3:5:44----purport).

After the three worlds—the upper, lower and middle planetary systems—merged into the water of dissolution, the living entities of all the three worlds remained in their subtle bodies by dint of the energy called kāla. In this dissolution, the gross bodies became unmanifest, but the subtle bodies existed, just like the water of the material creation. Thus the material energy was not completely wound up, as is the case in the full dissolution of the material world.
(Srimad Bhagavatam----3:8:11----purport).

The enlightened jñānī, when free from all material contaminations, namely the gross and subtle bodies together with the senses of the material modes of nature, is placed in the Supreme and is thus liberated from material bondage. The jñānīs and the devotees are actually in agreement up to the point of liberation from material contamination. But whereas the jñānīs remain pacified on the platform of simple understanding, the devotees develop further spiritual advancement in loving service. The devotees develop a spiritual individuality in their spontaneous service attitude, which is enhanced on and on, up to the point of mādhurya-rasa, or transcendental loving service reciprocated between the lover and the beloved.
(Srimad Bhagavatam----3:9:33----purport).

According to Śrīdhara Svāmī, Brahmā's constant dropping of his body does not refer to his actually giving up his body. Rather, he suggests that Brahmā gave up a particular mentality. Mind is the subtle body of the living entity. We may sometimes be absorbed in some thought which is sinful, but if we give up the sinful thought, it may be said that we give up the body. Brahmā's mind was not in correct order when he created the demons. It must have been full of passion because the entire creation was passionate; therefore such passionate sons were born. It follows that any father and mother should also be careful while begetting children. The mental condition of a child depends upon the mental status of his parents at the time he is conceived. According to the Vedic system, therefore, the garbhādhāna-saṁskāra, or the ceremony for giving birth to a child, is observed. Before begetting a child, one has to sanctify his perplexed mind. When the parents engage their minds in the lotus feet of the Lord and in such a state the child is born, naturally good devotee children come; when the society is full of such good population, there is no trouble from demoniac mentalities.
(Srimad Bhagavatam----3:20:28----purport).

Real individuality is to understand oneself to be the eternal servitor of the Supreme Lord. This information is received from the mouth of Lord Caitanya. He said clearly, upon the inquiry of Sanātana Gosvāmī, that a living entity is the servitor of Kṛṣṇa eternally. Kṛṣṇa also confirms in Bhagavad-gītā that the living entity is eternally His part and parcel. The part and parcel is meant to serve the whole. This is individuality. It is so even in this material existence, when the living entity apparently merges in matter. His gross body is made up of five elements, his subtle body is made of mind, intelligence, false ego and contaminated consciousness, and he has five active senses and five knowledge-acquiring senses. In this way he merges in matter. But even while merged in the twenty-four elements of matter, he can keep his individuality as the eternal servitor of the Lord. Either in the spiritual nature or in the material nature, such a servitor is to be considered a liberated soul.
(Srimad Bhagavatam----3:27:14----purport).

The words liṅgād vinirgame, which are used here, mean "after being freed from the two kinds of material bodies, subtle and gross." The subtle body is made of mind, intelligence, false ego and contaminated consciousness, and the gross body is made of five elements—earth, water, fire, air and ether. When one is transferred to the spiritual world, he gives up both the subtle and gross bodies of this material world. He enters the spiritual sky in his pure, spiritual body and is stationed in one of the spiritual planets. Although the impersonalists also reach that spiritual sky after giving up the subtle and gross material bodies, they are not placed in the spiritual planets; as they desire, they are allowed to merge in the spiritual effulgence emanating from the transcendental body of the Lord. The word sva-saṁsthānam is also very significant. As a living entity prepares himself, so he attains his abode. The impersonal Brahman effulgence is offered to the impersonalists, but those who want to associate with the Supreme Personality of Godhead in His transcendental form as Nārāyaṇa in the Vaikuṇṭhas, or with Kṛṣṇa in Kṛṣṇaloka, go to those abodes, wherefrom they never return.
(Srimad Bhagavatam----3:27:28-29----purport).

In a dream one may see himself expanded through many bodies, but when awake he can understand that those bodies were all false. Similarly, although a liberated soul has the by-products of the body-children, wife, house, etc.—he does not identify himself with those bodily expansions. He knows that they are all products of the material dream. The gross body is made of the gross elements of matter, and the subtle body is made of mind, intelligence, ego and contaminated consciousness. If one can accept the subtle body of a dream as false and not identify oneself with that body, then certainly an awake person need not identify with the gross body. As one who is awake has no connection with the activities of the body in a dream, an awakened, liberated soul has no connection with the activities of the present body. In other words, because he is acquainted with his constitutional position, he never accepts the bodily concept of life.
(Srimad Bhagavatam----3:27:28-38----purport).

Every living entity is covered by a subtle and gross body. The subtle body is the covering of mind, ego, intelligence and consciousness. It is said in the scriptures that the constables of Yamarāja cover the subtle body of the culprit and take him to the abode of Yamarāja to be punished in a way that he is able to tolerate. He does not die from this punishment because if he died, then who would suffer the punishment? It is not the business of the constables of Yamarāja to put one to death. In fact, it is not possible to kill a living entity because factually he is eternal; he simply has to suffer the consequences of his activities of sense gratification.
(Srimad Bhagavatam----3:30:20----purport).

One yojana is calculated to be eight miles, and he has to pass along a road which is therefore as much as 792,000 miles. Such a long distance is passed over within a few moments only. The subtle body is covered by the constables so that the living entity can pass such a long distance quickly and at the same time tolerate the suffering. This covering, although material, is of such fine elements that material scientists cannot discover what the coverings are made of. To pass 792,000 miles within a few moments seems wonderful to the modern space travelers. They have so far traveled at a speed of 18,000 miles per hour, but here we see that a criminal passes 792,000 miles within a few seconds only, although the process is not spiritual but material.
(Srimad Bhagavatam----3:30:24----purport).