And if we accept the Vedic conclusion as stated in the Bhagavad-gītā that these material bodies are perishable in due course of time (antavanta ime dehāḥ) but that the soul is eternal (nityasyoktāḥ śarīriṇaḥ), then we must remember always that the body is like a dress; therefore why lament the changing of a dress? The material body has no factual existence in relation to the eternal soul. It is something like a dream. In a dream we may think of flying in the sky, or sitting on a chariot as a king, but when we wake up we can see that we are neither in the sky nor seated on the chariot. The Vedic wisdom encourages self-realization on the basis of the nonexistence of the material body. Therefore, in either case, whether one believes in the existence of the soul or one does not believe in the existence of the soul, there is no cause for lamentation for loss of the body.
(Bhagavad-Gita----2:28----purport).

There are two classes of intelligent men. One is intelligent in material activities for sense gratification, and the other is introspective and awake to the cultivation of self-realization. Activities of the introspective sage, or thoughtful man, are night for persons materially absorbed. Materialistic persons remain asleep in such a night due to their ignorance of self-realization. The introspective sage remains alert in the "night" of the materialistic men. The sage feels transcendental pleasure in the gradual advancement of spiritual culture, whereas the man in materialistic activities, being asleep to self-realization, dreams of varieties of sense pleasure, feeling sometimes happy and sometimes distressed in his sleeping condition. The introspective man is always indifferent to materialistic happiness and distress. He goes on with his self-realization activities undisturbed by material reactions.
(Bhagavad-Gita----2:69----purport).

The senses are different outlets for the activities of lust. Lust is reserved within the body, but it is given vent through the senses. Therefore, the senses are superior to the body as a whole. These outlets are not in use when there is superior consciousness, or Kṛṣṇa consciousness. In Kṛṣṇa consciousness the soul makes direct connection with the Supreme Personality of Godhead; therefore the hierarchy of bodily functions, as described here, ultimately ends in the Supreme Soul. Bodily action means the functions of the senses, and stopping the senses means stopping all bodily actions. But since the mind is active, then even though the body may be silent and at rest, the mind will act—as it does during dreaming. But above the mind is the determination of the intelligence, and above the intelligence is the soul proper. If, therefore, the soul is directly engaged with the Supreme, naturally all other subordinates, namely, the intelligence, mind and senses, will be automatically engaged. In the Kaṭha Upaniṣad there is a similar passage, in which it is said that the objects of sense gratification are superior to the senses, and mind is superior to the sense objects. If, therefore, the mind is directly engaged in the service of the Lord constantly, then there is no chance that the senses will become engaged in other ways.
(Bhagavad-Gita----3:42----purport).

Anyone who eats for sense pleasure, or cooks for himself, not offering his food to Kṛṣṇa, eats only sin. One who eats sin and eats more than is allotted to him cannot execute perfect yoga. It is best that one eat only the remnants of foodstuff offered to Kṛṣṇa. A person in Kṛṣṇa consciousness does not eat anything which is not first offered to Kṛṣṇa. Therefore, only the Kṛṣṇa conscious person can attain perfection in yoga practice. Nor can one who artificially abstains from eating, manufacturing his own personal process of fasting, practice yoga. The Kṛṣṇa conscious person observes fasting as it is recommended in the scriptures. He does not fast or eat more than is required, and he is thus competent to perform yoga practice. One who eats more than required will dream very much while sleeping, and he must consequently sleep more than is required. One should not sleep more than six hours daily. One who sleeps more than six hours out of twenty-four is certainly influenced by the mode of ignorance. A person in the mode of ignorance is lazy and prone to sleep a great deal. Such a person cannot perform yoga.
(Bhagavad-Gita----6:18----purport).

The demonic conclude that the world is phantasmagoria. There is no cause and effect, no controller, no purpose: everything is unreal. They say that this cosmic manifestation arises due to chance material actions and reactions. They do not think that the world was created by God for a certain purpose. They have their own theory: that the world has come about in its own way and that there is no reason to believe that there is a God behind it. For them there is no difference between spirit and matter, and they do not accept the Supreme Spirit. Everything is matter only, and the whole cosmos is supposed to be a mass of ignorance. According to them, everything is void, and whatever manifestation exists is due to our ignorance in perception. They take it for granted that all manifestation of diversity is a display of ignorance. Just as in a dream we may create so many things which actually have no existence, so when we are awake we shall see that everything is simply a dream. But factually, although the demons say that life is a dream, they are very expert in enjoying this dream. And so, instead of acquiring knowledge, they become more and more implicated in their dreamland. They conclude that as a child is simply the result of sexual intercourse between man and woman, this world is born without any soul. For them it is only a combination of matter that has produced the living entities, and there is no question of the existence of the soul. As many living creatures come out from perspiration and from a dead body without any cause, the whole living world has come out of the material combinations of the cosmic manifestation. Therefore material nature is the cause of this manifestation, and there is no other cause. They do not believe in the words of Kṛṣṇa in Bhagavad-gītā: mayādhyakṣeṇa prakṛtiḥ sūyate sa-carācaram. "Under My direction the whole material world is moving." In other words, among the demons there is no perfect knowledge of the creation of the world; every one of them has some particular theory of his own.
(Bhagavad-Gita----16:8----purport).