When something uncommon happens in ones progressive spiritual life, it should be understood to be incurred by ajnata-sukrti, or pious activities beyond ones knowledge. To see personally the Supreme Personality of Godhead or His pure devotee is not an ordinary incident. When such things happen, they should be understood to be caused by previous pious activity, as confirmed in Bhagavad-gita (7.28): yesam tv anta-gatam papam jananam punya-karmanam. One who is completely freed from all the resultant actions of sinful activities and who is absorbed only in pious activities can engage in devotional service. Although Maharaja Prthus life was full of pious activities, he was wondering how his audience with the Kumaras happened. He could not imagine what kind of pious activities he had performed. This is a sign of humility on the part of King Prthu, whose life was so full of pious activities that even Lord Visnu came to see him and predicted that the Kumaras would also come.