Only dull people are brilliant at breakfast.

The epigram turns on Wilde’s characteristic inversion: what seems a virtue—being “brilliant” early in the day—is recast as a mark of dullness. Implicit is a dandyish, late-Victorian suspicion of earnest morning efficiency and a preference for wit that arrives with leisure, conversation, and social performance rather than with routine. The line also satirizes the idea of constant sparkle as a social obligation: if someone can be dazzling at breakfast, Wilde suggests, their “brilliance” may be mechanical or conventional rather than the product of genuine imagination. Like many Wildean aphorisms, it is less a literal claim than a comic critique of bourgeois propriety and predictable cleverness.