Why did Kisa Gotami, despite her desperate efforts to find a solution for her grief, ultimately become weary and hopeless ? (The Sermon at Benares)

Kisa Gotami’s only son died, wanted to bring him back to life didn’t find any medicine, went to Buddha for the cure he asked her to bring mustard seeds from a house where no one had died she went from house to house all day finally tired, sat on the wayside, weary and hopeless flickering lights and her experience during the day, made her to understand the inevitability of death