“无才便是德”中的“无”是动词，不是形容词

“无才” does not mean lacking talent, but rather “disabling” or “turning off” one’s talent. What does that mean?

Zhang San and Li Si were both top students with plenty of talent. During class, when they heard something they already understood, Zhang San would just smile knowingly; Li Si, however, would eagerly jump up and interrupt, disrupting the classroom order. Zhang San’s behavior is what we call “de” (virtue/moral character).

He has talent, but he deliberately puts it on hold. He knows when it’s appropriate to speak and when it’s not, understands that classroom discipline comes first, and recognizes that showing off must be timed well and read from the room. Li Si isn’t untalented—he simply failed to put his talent on hold. He showed off indiscriminately, no matter the occasion, which made him quite annoying. Li Si’s behavior is what we call “wu de” (immorality/lack of virtue).