The word kṛpaṇa-dhīḥ is significant in this verse. Dhī means "intelligence," and kṛpaṇa means "miserly." Conditional life is for persons who are of miserly intelligence or who do not properly utilize their intelligence. In the human form of life the intelligence is developed, and one has to utilize that developed intelligence to get out of the cycle of birth and death. One who does not do so is a miser, just like a person who has immense wealth but does not utilize it, keeping it simply to see. A person who does not actually utilize his human intelligence to get out of the clutches of māyā, the cycle of birth and death, is accepted as miserly. The exact opposite of miserly is udāra, "very magnanimous." A brāhmaṇa is called udāra because he utilizes his human intelligence for spiritual realization. He uses that intelligence to preach Kṛṣṇa consciousness for the benefit of the public, and therefore he is magnanimous.
(Srimad Bhagavatam----3:31:17----purport).

The child prays that it is better to remain within the womb of darkness and be constantly absorbed in Kṛṣṇa consciousness than to get out and again fall a victim to the illusory energy. The illusory energy acts within the abdomen as well as outside the abdomen, but the trick is that one should remain Kṛṣṇa conscious, and then the effect of such a horrible condition cannot act unfavorably upon him. In Bhagavad-gītā it is said that one's intelligence is his friend, and the same intelligence can also be his enemy. Here also the same idea is repeated: suhṛdātmanaiva, friendly intelligence. Absorption of intelligence in the personal service of Kṛṣṇa and full consciousness of Kṛṣṇa always are the path of self-realization and liberation. Without being unnecessarily agitated, if we take to the process of Kṛṣṇa consciousness by constantly chanting Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare/ Hare Rāma, Hare Rāma, Rāma Rāma, Hare Hare, the cycle of birth and death can be stopped for good.
(Srimad Bhagavatam----3:31:21----purport).

When the living entity is encaged in the material body, he is called jīva-bhūta, and when he is free from the material body he is called brahma-bhūta (S.B.4:30:20). By changing his material body birth after birth, he travels not only in the different species of life, but also from one planet to another. Lord Caitanya says that the living entities, bound up by fruitive activities, are wandering in this way throughout the whole universe, and if by some chance or by pious activities they get in touch with a bona fide spiritual master, by the grace of Kṛṣṇa, then they get the seed of devotional service. After getting this seed, if one sows it within his heart and pours water on it by hearing and chanting, the seed grows into a big plant, and there are fruits and flowers which the living entity can enjoy, even in this material world. That is called the brahma-bhūta stage. In his designated condition, a living entity is called materialistic, and upon being freed from all designations, when he is fully Kṛṣṇa conscious, engaged in devotional service, he is called liberated. Unless one gets the opportunity to associate with a bona fide spiritual master by the grace of the Lord, there is no possibility of one's liberation from the cycle of birth and death in the different species of life and through the different grades of planets.
(Srimad Bhagavatam----3:31:43----purport).

The Supreme Personality of Godhead is here described as hari-medhaḥ, or "He who can deliver one from the cycle of birth and death." Materialistic persons are never interested in hearing about the marvelous pastimes of the Lord. They think that they are fictions and stories and that the Supreme Godhead is also a man of material nature. They are not fit for advancing in devotional service, or Kṛṣṇa consciousness. Such materialistic persons are interested in newspaper stories, novels and imaginary dramas. The factual activities of the Lord, such as Lord Kṛṣṇa's acting in the Battle of Kurukṣetra, or the activities of the Pāṇḍavas, or the Lord's activities in Vṛndāvana or Dvārakā, are related in the Bhagavad-gītā and Śrīmad-Bhāgavatam, which are full of the activities of the Lord. But materialistic persons who engage in elevating their position in the material world are not interested in such activities of the Lord. They may be interested in the activities of a great politician or a great rich man of this world, but they are not interested in the transcendental activities of the Supreme Lord.
(Srimad Bhagavatam----3:32:18----purport).

As stated by Lord Caitanya Mahāprabhu in His Śikṣāṣṭaka instructions, by the chanting of the holy name of the Lord—Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare/ Hare Rāma, Hare Rāma, Rāma Rāma, Hare Hare—or by the process of hearing and chanting of the glories of the Lord, one's mind is gradually cleansed of all dirt. Due to our material association since time immemorial, we have accumulated heaps of dirty things in our minds. The total effect of this takes place when a living entity identifies himself with his body and is thus entrapped by the stringent laws of material nature and put into the cycle of repeated birth and death under the false impression of bodily identification. When one is strengthened by practicing bhakti-yoga, his mind is cleansed of this misunderstanding, and he is no longer interested in material existence or in sense gratification.
(Srimad Bhagavatam----3:21:32----purport).

At present the whole world is on the verge of retiring from a blind materialistic civilization, which may be likened to hunting animals in the forest. People should take advantage of this Kṛṣṇa consciousness movement and leave their troublesome life of killing. It is said that the killers of animals should neither live nor die. If they live only to kill animals and enjoy women, life is not very prosperous. And as soon as a killer dies, he enters the cycle of birth and death in the lower species of life. That also is not desirable. The conclusion is that killers should retire from the killing business and take to this Kṛṣṇa consciousness movement to make life perfect. A confused, frustrated man cannot get relief by committing suicide because suicide will simply lead him to take birth in the lower species of life or to remain a ghost, unable to attain a gross material body. Therefore the perfect course is to retire altogether from sinful activities and take up Kṛṣṇa consciousness. In this way one can become completely perfect and go back home, back to Godhead.
(Srimad Bhagavatam----4:26:10----purport).

There are two ways of animal-killing. One way is in the name of religious sacrifices. All the religions of the world—except the Buddhists—have a program for killing animals in places of worship. According to Vedic civilization, the animal-eaters are recommended to sacrifice a goat in the temple of Kālī under certain restrictive rules and regulations and eat the flesh. Similarly, they are recommended to drink wine by worshiping the goddess Caṇḍikā. The purpose is restriction. People have given up all this restriction. Now they are regularly opening wine distilleries and slaughterhouses and indulging in drinking alcohol and eating flesh. A Vaiṣṇava ācārya like Nārada Muni knows very well that persons engaged in such animal-killing in the name of religion are certainly becoming involved in the cycle of birth and death, forgetting the real aim of life: to go home, back to Godhead.
(Srimad Bhagavatam----4:27:11----purport).

Originally the living entity is a spiritual being, but when he actually desires to enjoy this material world, he comes down. From this verse we can understand that the living entity first accepts a body that is human in form, but gradually, due to his degraded activities, he falls into lower forms of life—into the animal, plant and aquatic forms. By the gradual process of evolution, the living entity again attains the body of a human being and is given another chance to get out of the process of transmigration. If he again misses his chance in the human form to understand his position, he is again placed in the cycle of birth and death in various types of bodies.
(Srimad Bhagavatam----4:29:4----purport).

Unless one is properly trained, he becomes a victim of the modes of material nature, as confirmed by Bhagavad-gītā (3.27):
prakṛteḥ kriyamāṇāni
guṇaiḥ karmāṇi sarvaśaḥ
ahaṅkāra-vimūḍhātmā
kartāham iti manyate
"The bewildered spirit soul, under the influence of the three modes of material nature, thinks himself the doer of activities that are in actuality carried out by nature." As soon as one desires to enjoy his senses, he puts himself under the control of material energy and automatically, or mechanically, is placed into the cycle of birth and death in various life-forms
(Srimad Bhagavatam----4:29:4----purport).

Anarthas, unwanted things, come down from one bodily life to another. To get out of this entanglement, one has to take to the devotional service of Lord Vāsudeva, Kṛṣṇa, the Supreme Personality of Godhead. The word guru is significant in this connection. The word guru may be translated as "heavy," or "the supreme." In other words, the guru is the spiritual master. Śrīla Ṛṣabhadeva advised His sons, gurur na sa syāt. .. na mocayed yaḥ samupeta-mṛtyum: "One should not take up the post of spiritual master unless he is able to lead his disciple from the cycle of birth and death." (S.B.5:5:18) Material existence is actually a chain of action and reaction brought about by different types of fruitive activities. This is the cause of birth and death. One can stop this process only by engaging oneself in the service of Vāsudeva.
(Srimad Bhagavatam----4:29:36-37----purport).

Unless one becomes a devotee of the Lord, or becomes fully Kṛṣṇa conscious, he will certainly hover on the mental platform and be promoted and degraded in different types of bodies. All qualities that are considered good according to the material estimation actually have no value because these so-called good qualities will not save a person from the cycle of birth and death. The conclusion is that one should be without mental desire. Anyābhilāṣitā-śūnyaṁ jñāna-karmādy-anāvṛtam: (CC.2:19:167) one should be fully free from material desires, philosophical speculation and fruitive activity. The best course for a human being is to favorably accept the transcendental devotional service of the Lord. That is the highest perfection of human life.
(Srimad Bhagavatam----4:29:66----purport).