Kṛṣṇa is the cause of all causes (sarva-kāraṇa-kāraṇam), but one who has no connection with Kṛṣṇa is disturbed by immediate causes and cannot restrain his vision of separation or differences. When an expert physician treats a patient, he tries to find the original cause of the disease and is not diverted by the symptoms of that original cause. Similarly, a devotee is never disturbed by reverses in life. Tat te ’nukampāṁ susamīkṣamāṇaḥ (Bhāg. 10.14.8). A devotee understands that when he is in distress, this is due to his own past misdeeds, which are now accruing reactions, although by the grace of the Supreme Personality of Godhead these are only very slight. Karmāṇi nirdahati kintu ca bhakti-bhājām (Brahma-saṁhitā 5.54). When a devotee under the protection of the Supreme Personality of Godhead is to suffer because of faults in his past deeds, he passes through only a little misery by the grace of the Lord. Although the disease of a devotee is due to mistakes committed sometime in the past, he agrees to suffer and tolerate such miseries, and he depends fully on the Supreme Personality of Godhead. Thus he is never affected by material conditions of lamentation, jubilation, fear and so on. A devotee never sees anything to be unconnected with the Supreme Personality of Godhead. Śrīla Madhvācārya, quoting from the Bhaviṣya Purāṇa, says:

bhagavad-darśanād yasya
 virodhād darśanaṁ pṛthak
pṛthag-dṛṣṭiḥ sa vijñeyo
 na tu sad-bheda-darśanaḥ