A lie that is half-truth is the darkest of all lies.

The line warns that deception becomes especially potent when it is mixed with truth. A “half-truth” borrows credibility from what is accurate, making the false portion harder to detect and more likely to be believed. In that sense it can be “darkest”: it corrupts trust while appearing reasonable, and it can mislead conscientious people who would reject an obvious lie. The aphorism also implies an ethical critique of selective disclosure—telling only the convenient part of the truth can function as a deliberate manipulation, not an innocent omission. Its enduring appeal lies in how it captures a common mechanism of propaganda, spin, and self-justification.