BEDEVERE: Tell me … what do you do with witches?
CROWD: Burn them.
BEDEVERE: And what do you burn, apart from witches?
FOURTH VILLAGER: … Wood?
BEDEVERE: So why do witches burn?
SECOND VILLAGER: (quietly) … Because they’re made of wood?
BEDEVERE: Good. So how can we tell if she is made of wood?
FIRST VILLAGER: Make a bridge out of her.
BEDEVERE: Ah … but can you not also make bridges out of stone?
CROWD: Ah. Yes, of course … um … err …
BEDEVERE: Does wood sink in water?
CROWD: No, no, It floats. Throw her in the pond Tie weights on her. To the pond.
BEDEVERE: Wait. Wait … tell me, what also floats on water?
CROWD: Bread? No, no, no. Apples …. gravy … very small rocks …
ARTHUR: A duck.
BEDEVERE: Exactly. So… logically …
FIRST VILLAGER: If she … weighs the same as a duck … she’s made of wood.
BEDEVERE : And therefore?
CROWD: A witch!
—Monty Python and the Holy Grail