One day an old woman was traveling alone in the mountains. Suddenly she saw something shining  in the stream. When she came close, she found it was a precious  stone. She put the stone into her bag and went on with her trip. The next day the old woman met a young man, who was also a traveler in the mountains. The young man looked very hungry, so the old woman opened her bag to share her food. The hungry traveler saw the precious stone and asked carefully, "The stone is beautiful. Would you like to give it to me?" "Sure. Why not?" the woman said, and handed the stone to him. The young man left happily with the stone. He knew it was worth enough to give him _ for a lifetime. But a few days later he came back to return the stone to the woman. "I've been thinking," he said. "I know how valuable the stone is, but I give it back and hope that you can give me something even more precious. Give me what you have within your bag." The woman opened her bag. It was almost empty. She looked at the young man and smiled, "I have nothing special in my bag, but I do have something precious -- the joy of giving!" The young man felt ashamed  and left silently. The man returned the stone to the woman because   _  .
he found the stone was not precious he understood the real meaning of joy he felt embarrassed at taking away the stone he wanted to get something even more precious