You and a friend are by a swiftly moving river and suddenly hear the cries of a drowning child. You both jump in. After struggling through the current, you pull the kid to shore. 

 

But no sooner have you caught your breath than you hear another child call out. The two of you jump in again and save her, only to hear another cry for help, then another, then another, then another. Suddenly, your friend gets out of the water and starts to leave. Confused, you ask where he’s going. He replies: “I’m going upstream to tackle the guy who’s throwing all these kids in the water.”