What part of the rhetoric does the sentence “Medicine is good only if it is good” belong to it?

This sentence is a pun in rhetoric. Figures of speech generally refer to rhetorical techniques, including metaphor, comparison, metonymy, linking, hyperbole, pun, foil, displacement, parallelism, parallelism, and imitation. "Good medicinal materials are good" means one meaning on the surface and another meaning secretly. It is a rhetorical technique of pun. When a pun intentionally expresses one meaning on the surface, there is another meaning secretly, and the latter is the expression. the real intention of the person. Therefore, the sentence "medicine is good only if it is good" is a pun in rhetoric.