The Supreme Lord is so kind to His pure devotees that in proper time He calls such devotees up to Him and thus creates an auspicious circumstance for the devotee. Mahārāja Parīkṣit was a pure devotee of the Lord, and there was no reason for him to become extremely fatigued, hungry and thirsty because a devotee of the Lord never becomes perturbed by such bodily demands. But by the desire of the Lord, even such a devotee can become apparently fatigued and thirsty just to create a situation favorable for his renunciation of worldly activities. One has to give up all attachment for worldly relations before one is able to go back to Godhead, and thus when a devotee is too much absorbed in worldly affairs, the Lord creates a situation to cause indifference. The Supreme Lord never forgets His pure devotee, even though he may be engaged in so-called worldly affairs. Sometimes He creates an awkward situation, and the devotee becomes obliged to renounce all worldly affairs. The devotee can understand by the signal of the Lord, but others take it to be unfavorable and frustrating. Mahārāja Parīkṣit was to become the medium for the revelation of Śrīmad-Bhāgavatam by Lord Śrī Kṛṣṇa, as his grandfather Arjuna was the medium for the Bhagavad-gītā. Had Arjuna not been taken up with an illusion of family affection by the will of the Lord, the Bhagavad-gītāwould not have been spoken by the Lord Himself for the good of all concerned. Similarly, had Mahārāja Parīkṣit not been fatigued, hungry and thirsty at this time, Śrīmad-Bhāgavatam would not have been spoken by Śrīla Śukadeva Gosvāmī, the prime authority of Śrīmad-Bhāgavatam. So this is a prelude to the circumstances under which Śrīmad-Bhāgavatam was spoken for the benefit of all concerned. The prelude, therefore, begins with the words “once upon a time.”