Hiranyakasipu did not ask his young son anything that would be very difficult for him to answer; instead, he gave the boy a chance to speak plainly about whatever he thought might be best. Prahlada Maharaja, of course, being a perfect devotee, knew everything and could say what the best part of life is. In the Vedas it is said, yasmin vijnate samam evam vijnatam bhavati: if one properly understands God, he can understand any subject matter very nicely. Sometimes we have to challenge big scientists and philosophers, but by the grace of Krsna we emerge successful. It is impossible, practically speaking, for ordinary men to challenge scientists or philosophers concerning genuine knowledge, but a devotee can challenge them because the best of everything is known to a devotee by the grace of Krsna. As confirmed in Bhagavad-gita (10.11):