In the past, a man bragged about his bow: "There is no bow better than mine. It doesn't need any arrow!"
Another man bragged about his arrow: "There is no arrow better than mine. It doesn't need any bow!"
A skilled archer happened to pass by and heard them. He said, "You are both wrong. One cannot shoot an arrow without a bow, and without an arrow, how can one hit the target?"
He then asked them for their bow and arrow and demonstrated how to shoot at a target.
They finally understood: A bow is useless without an arrow, and an arrow is useless without a bow. They complement each other.