Kaṁsa considered that if he killed his sister, while living he would be condemned by everyone, and after death he would go to the darkest region of hellish life because of his cruelty. It is said that a cruel person like a butcher is advised not to live and not to die. While living, a cruel person creates a hellish condition for his next birth, and therefore he should not live; but he is also advised not to die, because after death he must go to the darkest region of hell. Thus in either circumstance he is condemned. Kaṁsa, therefore, having good sense about the science of the soul’s transmigration, deliberately refrained from killing Devakī.

In this verse the words gantā tamo ’ndhaṁ tanu-mānino dhruvam are very important and require extensive understanding. Śrīla Jīva Gosvāmī, in his Vaiṣṇava-toṣaṇī-ṭīkā, says, tatra tanu-māninaḥ pāpina iti dehātma-buddhyaiva pāpābhiniveśo bhavati: “One who lives in the bodily concept, thinking, ‘I am this body,’ involves himself, by the very nature of this conception, in a life of sinful activities. Anyone living in such a conception is to be considered a candidate for hell.”

adānta-gobhir viśatāṁ tamisraṁ
 punaḥ punaś carvita-carvaṇānām

(Bhāg. 7.5.30)

One who is in a bodily concept of life has no control over sense gratification. Such a person can do anything sinful to eat, drink, be merry and enjoy a life of sense gratification, not knowing of the soul’s transmigration from one body to another. Such a person does whatever he likes, whatever he imagines, and therefore, being subject to the laws of nature, he suffers miserably again and again in different material bodies.

yāvat kriyās tāvad idaṁ mano vai
 karmātmakaṁ yena śarīra-bandhaḥ

(Bhāg. 5.5.5)

In the bodily concept of life, a person is karmānubandha, or conditioned by karma, and as long as the mind is absorbed in karma, one must accept a material body. Śarīra-bandha, bondage to the material body, is a source of misery (kleśa-da).

na sādhu manye yata ātmano ’yam
 asann api kleśada āsa dehaḥ

(Bhāg. 5.5.4)

Although the body is temporary, it always gives one trouble in many ways, but human civilization is now unfortunately based on tanu-mānī, the bodily concept of life, by which one thinks, “I belong to this nation,” “I belong to this group,” “I belong to that group,” and so on. Each of us has his own ideas, and we are becoming increasingly involved, individually, socially, communally and nationally, in the complexities of karmānubandha, sinful activities. For the maintenance of the body, men are killing so many other bodies and becoming implicated in karmānubandha. Therefore Śrīla Jīva Gosvāmī says that tanu-mānī, those in the bodily concept of life, are pāpī, sinful persons. For such sinful persons, the ultimate destination is the darkest region of hellish life (gantā tamo ’ndham). In particular, a person who wants to maintain his body by killing animals is most sinful and cannot understand the value of spiritual life. In Bhagavad-gītā (16.19-20) the Lord says:

tān ahaṁ dviṣataḥ krūrān
 saṁsāreṣu narādhamān
kṣipāmy ajasram aśubhān
 āsurīṣv eva yoniṣu

āsurīṁ yonim āpannā
 mūḍhā janmani janmani
mām aprāpyaiva kaunteya
 tato yānty adhamāṁ gatim

“Those who are envious and mischievous, who are the lowest among men, are cast by Me into the ocean of material existence, into various demoniac species of life. Attaining repeated birth among the species of demoniac life, such persons can never approach Me. Gradually they sink down to the most abominable type of existence.” A human being is meant to understand the value of human life, which is a boon obtained after many, many births. Therefore one must free oneself from tanu-mānī, the bodily concept of life, and realize the Supreme Personality of Godhead.