Poppa, a talking bear, was best friends with a lonely caveman who suffered from constant mood swings. Poppa tried many things to cheer up his friend when he became sad, but nothing worked. One winter night, as the caveman cried inside their cave, Poppa discovered how to make fire by rubbing two sticks together. When Poppa showed the caveman the fire's warm, orange flames, his mood immediately lifted and he smiled. Poppa realized that darkness was what made his friend sad, while light cheered him up. From then on, Poppa would light fires at night to keep his caveman friend happy.