SB 1.17.18

na vayaṁ kleśa-bījāni
 yataḥ syuḥ puruṣarṣabha
puruṣaṁ taṁ vijānīmo
 vākya-bheda-vimohitāḥ
Word for word: 
na — not; vayam — we; kleśa-bījāni — the root cause of sufferings; yataḥ — wherefrom; syuḥ — it so happens; puruṣa-ṛṣabha — O greatest of all human beings; puruṣam — the person; tam — that; vijānīmaḥ — know; vākya-bheda — difference of opinion; vimohitāḥ — bewildered by.
Translation: 
O greatest among human beings, it is very difficult to ascertain the particular miscreant who has caused our sufferings, because we are bewildered by all the different opinions of theoretical philosophers.
Purport: 

There are many theoretical philosophers in the world who put forward their own theories of cause and effect especially about the cause of suffering and its effect on different living beings. Generally there are six great philosophers: Kaṇāda, the author of Vaiśeṣika philosophy; Gautama, the author of logic; Patañjali, the author of mystic yoga; Kapila, the author of Sāṅkhya philosophy; Jaimini, the author of Karma-mīmāṁsā; and Vyāsadeva, the author of Vedānta-darśana.

Although the bull, or the personality of religion, and the cow, the personality of the earth, knew perfectly well that the personality of Kali was the direct cause of their sufferings, still, as devotees of the Lord, they knew well also that without the sanction of the Lord no one could inflict trouble upon them. According to the Padma Purāṇa, our present trouble is due to the fructifying of seedling sins, but even those seedling sins also gradually fade away by execution of pure devotional service. Thus even if the devotees see the mischief-mongers, they do not accuse them for the sufferings inflicted. They take it for granted that the mischief-monger is made to act by some indirect cause, and therefore they tolerate the sufferings, thinking them to be God-given in small doses, for otherwise the sufferings should have been greater.

Mahārāja Parīkṣit wanted to get a statement of accusation against the direct mischief-monger, but they declined to give it on the above-mentioned grounds. Speculative philosophers, however, do not recognize the sanction of the Lord; they try to find out the cause of sufferings in their own way, as will be described in the following verses. According to Śrīla Jīva Gosvāmī, such speculators are themselves bewildered, and thus they cannot know that the ultimate cause of all causes is the Supreme Lord, the Personality of Godhead.