The great ages of prose are the ages in which men shave. The great ages of poetry are those in which they allow their beards to grow.

Lynd wittily links literary temper to fashion, using shaving versus beards as a shorthand for cultural mood. “Prose” suggests clarity, restraint, and civic practicality—qualities he associates with tidy, controlled self-presentation. “Poetry,” by contrast, is aligned with romanticism, prophecy, or bohemian intensity, signaled by the beard as emblem of nonconformity and imaginative excess. The point is not a literal causal claim about grooming, but a satirical way of describing how periods of literature often coincide with broader ideals of masculinity, decorum, and social order. The epigram also hints that aesthetic styles recur in cycles: disciplined, rational phases followed by more expressive, untamed ones.