What is play to one is death to another

There was a pond full of frogs. Some of them put their heads out of the water and croaked loudly. One day some boys were playing by the side of the pond. When they heard the frogs croaking, they began to throw stones at them. All the frogs at once went down into the water. But the boys remained standing there with stones in there hands. The new game was a great fun to them. They went on pelting the frogs with stones when they raised their heads above the water. Thus many frogs were hit, hard and few were killed. At last an old frog raised its head and said,"Oh boys, please! Please, stop the cruel fun. Don't throw stones at us." "It is a play. We are enjoying it." said the boys. "Why should we stop it?" "What is play to you is death to us. This is why, you should stop it," answered the old frog. The boys were ashamed of this. They left the cruel game and went away.