Teacher: "boys, do someone of you know a story with a moral?"
Student: "yeah, I know one"
"Once there was a knight, that challenged to duel a mysterious Black Knight. The Black Knight killed him.
So the 3 sons of the first knight, challenged to duel the Black Knight, to avenge their father, but the Black Knight killed them all.
So the 4 brothers of the first knight, challenged to duel the Black Knight, but the Black Knight killed them all.
So the 12 sons of the 4 brothers, challenged to duel the Black Knight, but the Black Knight killed them all.
So the 24 friends of the 12 sons, challenged to duel the Black Knight, but the Black Knight killed them all.
So the 24 fathers of..."
Teacher: "yeah, I think I've got the picture... but what should be the moral?"
Student: "that you don't mess with the Black Knight".