A witch is a female who burns.
Witches burn – because they're made of wood.
Wood floats. What else floats on water?
A duck; if something has the same weight as a duck it must float.
A duck and scales are fetched.
The girl and the duck balance perfectly.
"It's a fair cop."
Monty Python and the Holy Grail (1975)
Sir Bedevere (etc.)
Mr. Blint (a village n'er do well very keen on burning witches) (etc.)
Mr. Newt (a village blacksmith quite interested in burning witches) (etc.)
Mr. Duck (a village carpenter who is almost keener
than anyone else to burn witches) (etc.)