The real sting here lies in recognizing that *most people* believe they already know their limits—and that false certainty is precisely what traps them. A surgeon who understands exactly which cases fall outside her expertise will refer patients appropriately; a surgeon who *thinks* she knows her boundaries but doesn't may attempt something she cannot execute. Confucius is pointing to something subtler than mere humility: he's suggesting that genuine mastery requires an almost uncomfortable clarity about where your competence ends, which demands constant self-examination rather than settled self-knowledge.