SB 7.13.30
dehadibhir daiva-tantrair
atmanah sukham ihatah
duhkhatyayam canisasya
kriya moghah krtah krtah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The living entity tries to achieve happiness and rid himself of the causes of distress, but because the various bodies of the living entities are under the full control of material nature, all his plans in different bodies, one after another, are ultimately baffled.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Because the materialist is in gross ignorance of how the laws of material nature act upon him as a result of his fruitive activity, he mistakenly plans to enjoy bodily comfort in the human form of life through so-called economic development, through pious activities for elevation to the higher planetary systems, and in many other ways, but factually he becomes a victim of the reactions of his fruitive activities. The Supreme Personality of Godhead is situated as the Supersoul within the cores of the hearts of all living entities. As the Lord says in Bhagavad-gita (15.15):
sarvasya caham hrdi sannivisto
mattah smrtir jñanam apohanam ca
“I am seated in everyone’s heart, and from Me come remembrance, knowledge and forgetfulness.” The desires and activities of the living being are observed by the Supersoul, who is the upadrasta, the overseer, and who orders material nature to fulfill the various desires of the living being. As clearly stated in Bhagavad-gita (18.61):
isvarah sarva-bhutanam
hrd-dese ’rjuna tisthati
bhramayan sarva-bhutani
yantrarudhani mayaya
The Lord is situated in everyone’s heart, and as one desires, the Lord gives one various types of bodies, which are like machines. Riding on such a machine, the living entity wanders throughout the universe, under the control of material nature and its modes. Thus the living being is not at all free to act, but is fully under the control of material nature, which is fully under the control of the Supreme Personality of Godhead.
As soon as a living entity is victimized by material desires to lord it over material nature, he is subjected to the control of material nature, which is supervised by the Supreme Soul. The result is that one again and again makes plans and is baffled, but as foolish as he is he cannot see the cause of his bafflement. This cause is distinctly stated in Bhagavad-gita: because one has not surrendered to the Supreme Personality of Godhead, he must work under the control of material nature and its stringent laws (daivi hy esa gunamayi mama maya duratyaya). The only means of becoming free from this entanglement is to surrender to the Supreme Lord. In the human form of life, the living entity must accept this instruction from the Supreme Person, Krsna: sarva-dharman parityajya mam ekam saranam vraja. “Do not plan to achieve happiness and drive away distress. You will never be successful. Simply surrender unto Me.” Unfortunately, however, the living entity does not accept the Supreme Lord’s clearly stated instructions from Bhagavad-gita, and thus he becomes a perpetual captive of the laws of material nature.
Yajñarthat karmano ’nyatra loko ’yam karma-bandhanah: if one does not act for the satisfaction of Krsna, who is known as Visnu or Yajña, he must be entangled in the reactions of fruitive activities. These reactions are called papa and punya — sinful and pious. By pious activities one is elevated to the higher planetary systems, and by impious activities one is degraded to lower species of life, in which he is punished by the laws of nature. In the lower species of life there is an evolutionary process, and when the term of the living entity’s imprisonment or punishment in the lower species is finished, he is again offered a human form and given a chance to decide for himself which way he should plan. If he again misses the opportunity, he is again put into the cycle of birth and death, going sometimes higher and sometimes lower, turning on the samsara-cakra, the wheel of material existence. As a wheel sometimes goes up and sometimes comes down, the stringent laws of material nature make the living entity in material existence sometimes happy and sometimes distressed. How he suffers in the cycle of happiness and distress is described in the next verse.