SB 6.5.15

tat-saṅga-bhraṁśitaiśvaryaṁ
 saṁsarantaṁ kubhāryavat
tad-gatīr abudhasyeha
 kim asat-karmabhir bhavet
Word for word: 
tat-saṅga — by association with the prostitute of intelligence; bhraṁśita — taken away; aiśvaryam — the opulence of independence; saṁsarantam — undergoing the material way of life; ku-bhārya-vat — exactly like a person who has a polluted wife; tat-gatīḥ — the movements of the polluted intelligence; abudhasya — of one who does not know; iha — in this world; kim asat-karmabhiḥ bhavet — what can be the benefit of performing temporary fruitive activities.
Translation: 
[Nārada Muni had also spoken of a man who is the husband of the prostitute. The Haryaśvas understood this as follows.] If one becomes the husband of a prostitute, he loses all independence. Similarly, if a living entity has polluted intelligence, he prolongs his materialistic life. Frustrated by material nature, he must follow the movements of the intelligence, which brings various conditions of happiness and distress. If one performs fruitive activities under such conditions, what will be the benefit?
Purport: 

Polluted intelligence has been compared to a prostitute. One who has not purified his intelligence is said to be controlled by that prostitute. As stated in Bhagavad-gītā (2.41), vyavasāyātmikā buddhir ekeha kuru-nandana: those who are actually serious are conducted by one kind of intelligence, namely, intelligence in Kṛṣṇa consciousness. Bahu-śākhā hy anantāś ca buddhayo ’vyavasāyinām: one who is not fixed in proper intelligence discovers many modes of life. Thus involved in material activities, he is exposed to the different modes of material nature and subjected to varieties of so-called happiness and distress. If a man becomes the husband of a prostitute, he cannot be happy, and similarly one who follows the dictations of material intelligence and material consciousness will never be happy.

One must judiciously understand the activities of material nature. As stated in 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 to be the doer of activities, which are in actuality carried out by nature.” Although one follows the dictations of material nature, he happily thinks himself the master or husband of material nature. Scientists, for example, try to be the masters of material nature, life after life, not caring to understand the Supreme Person, under whose direction everything within this material world is moving. Trying to be the masters of material nature, they are imitation gods who declare to the public that scientific advancement will one day be able to avoid the so-called control of God. In fact, however, the living being, unable to control the rulings of God, is forced to associate with the prostitute of polluted intelligence and accept various material bodies. As stated in Bhagavad-gītā (13.22):

puruṣaḥ prakṛti-stho hi
 bhuṅkte prakṛti-jān guṇān
kāraṇaṁ guṇa-saṅgo ’sya
 sad-asad-yoni-janmasu

“The living entity in material nature thus follows the ways of life, enjoying the three modes of nature. This is due to his association with that material nature. Thus he meets with good and evil amongst various species.” If one fully engages in temporary fruitive activities and does not solve this real problem, what profit will he gain?