A moneylender wants to forgive a farmer's debt if he can marry his daughter. He puts two black pebbles in a bag and tells the daughter to pick one - if she picks black, she must marry him, but if white, she is free. The daughter notices both pebbles are black. Rather than pick, she takes one out and drops it, then tells him to check the bag, knowing the remaining pebble must be black, allowing her to claim she picked the white one. This solves her dilemma through lateral thinking rather than conventional solutions.