A mental stain can neither be blotted out by the passage of time nor washed away by any waters.

The line uses a vivid metaphor—guilt or moral wrongdoing as a “stain” on the mind—to argue that ethical damage is not automatically erased by time or by external cleansing rituals. It implies that conscience and memory preserve the mark of shame, and that true moral repair requires something deeper than waiting, forgetting, or symbolic purification. In a Ciceronian frame, this aligns with the Roman emphasis on honor (existimatio) and the inner tribunal of conscience: reputational or psychological consequences can persist even when legal penalties lapse or public attention fades. The quote is often invoked to stress accountability and the enduring nature of remorse.