Sometimes simply the Latin term for allegory.
However, the Ad Herennium author defines permutatio in three ways. The
first of these is akin to the conventional understanding of allegory,
while the other two are comparisons involving allusions.
- permutatio by comparison
Employing several metaphors drawn from the same domain together.
After the most recent threats from abroad, the president
claimed the dogs of war were barking up the wrong tree, and if they
weren't careful, they'd find themselves more neutered than neutral.
- permutatio by argument
Employing a comparison in order to magnify or lessen.
Said to Dan Quayle during the Vice-presidential debates:
"Senator, you're no Jack Kennedy."
- permutatio by contrast
Employing a mocking comparison.
Said to a penny pincher:
Thanks for your philanthropy, buddy.
Ad Herennium 4.34.46