All that is not prose is verse; and all that is not verse is prose.

The line draws a sharp, almost comic boundary between the two dominant literary modes in early modern European writing: prose and verse. Read as a witticism, it suggests that attempts to define poetry by lofty qualities (inspiration, beauty, moral elevation) can collapse into a simple formal distinction: if it isn’t arranged as verse, it’s prose—and vice versa. Attributed to Molière, it also fits the satirical spirit of French classical comedy, where pedantry about “rules” of style is often mocked. The remark can be taken as a critique of over-theorizing literature, implying that some classifications are tautological rather than illuminating.