What makes this aphorism sting is that it's not really about willpower at all—it's about the peculiar truth that belief operates as its own evidence. The man convinced of his inability hasn't simply given up; he's already gathered plenty of proof, however selectively, to confirm what he already assumes. When a musician tells herself she's tone-deaf and therefore skips the audition, she never gets the corrective experience that might prove her wrong; the prophecy fulfills itself. Confucius understood something modern psychology keeps rediscovering: that the script we write about ourselves becomes indistinguishable from fact, not because the universe bends to our thoughts, but because we stop trying where we've already decided failure waits.