Two friends argued while walking through the desert, resulting in one slapping the other. The slapped friend wrote in the sand about the incident but did not confront his friend. Later, at an oasis, the same friend was saved from drowning by the other. Grateful, he wrote about the rescue on a stone. When asked why he wrote in different mediums, the friend explained that hurts should be written in sand to be erased by forgiveness, while acts of goodwill should be engraved in stone to never be forgotten.