A big fire reduced the laboratory of the great inventor Edison to ashes. At the height of the fire, Edison's son Charlie frantically searched for his father in the smoke and ruins. Finally, he saw his father calmly looking at the fire, his face shining in the flickering flames, and his white hair fluttering in the cold wind. The next morning, Edison looked at the ruins and said, "Disaster also has its value. You see, all our previous mistakes were completely destroyed by the fire. Thank God, now we can start all over again. "