Once upon a time, a man passing by a river saw a grown man about to throw a child he was carrying into the water.
The child was terrified, crying and screaming in panic.
The passerby asked, "Why are you throwing this child into the river? Aren't you afraid he will drown?"
The man replied, "It's fine. His father is an excellent swimmer."
The passerby then asked, "His father can swim, but does that mean his son can swim without any practice?"