There are only two kinds of people who reliably cannot interpret figurative language as such, confusing metaphor or hyperbole with literal sense. They are schizophrenics and, apparently, political conservatives.
It has long been a basis of psychiatric diagnosis to ask a subject to interpret a proverb. If they interpret it literally, that tends to favor a diagnosis of schizophrenia. “A rolling stone gathers no moss” is a favorite. A literal interpretation would consist of an explanation of how moss grows more easily on stationary objects. A “normal” interpretation makes use of metaphor: someone who has put down no roots and has no connections to others will not be saddled with responsibilities, and/or will not amass property or meaningful relationships. Continue reading